Etea Mdcat 2008 — Solved Past Paper with Answers

Q1. The students were _ and the teacher, therefore did not take the class.

• A. Only few
• B. Few✓
• C. No much
• D. Very few

Explanation: The correct answer is 'Few.' The sentence uses 'therefore,' indicating a consequence or result. The word 'few' implies that the number of students was insufficient, leading to the teacher's decision not to take the class. 'Only few' is not a standard English expression, 'No much' is grammatically incorrect, and 'Very few' is overly specific and not required to convey the intended meaning.

Q2. A person who hates other people and avoids human to society is known as:

• A. Misanthrope✓
• B. Inhuman
• C. Sadist
• D. Misogynist

Explanation: 'Misanthrope' is someone who dislikes or avoids other people because of their general hatred,distrust or contempt toward humans ,human behavior or nature.

Q3. ‘Blow great trumpet / horn’ refers to:

• A. Boast✓
• B. Violent flow of word
• C. Celebrate enthusiastically
• D. Eruption

Explanation: The phrase ‘Blow great trumpet / horn’ is idiomatic and means to boast. It involves talking about one's own achievements with the intention to impress others. The correct answer is 'Boast' because it aligns with this meaning. The other options do not fit the idiomatic expression: 'Violent flow of word' suggests aggressive speech rather than boasting; 'Celebrate enthusiastically' implies joy and group activity, not personal boasting; 'Eruption' signifies a sudden release, unrelated to the context of boasting.

Q4. Many ancient civilizations _ on the banks of major rivers:

• A. Dashed
• B. Flourished✓
• C. Sprawled
• D. Succeeded

Explanation: Flourished means prosper, grow or thrive.

Q5. Which one is an auxiliary?

• A. With
• B. On
• C. Do✓
• D. For

Explanation: The correct answer is 'Do.' In this question, 'Do' is the only auxiliary verb among the options provided. Auxiliary verbs, also known as helping verbs, are used alongside main verbs to create questions, negative statements, and various verb tenses. The other options, 'With,' 'On,' and 'For,' are prepositions that show the relationship between nouns or pronouns and other elements in a sentence.

Q6. To have a windfall refers to:

• A. Bad weather
• B. Receiving gifts
• C. Receiving profits✓
• D. Sudden calamity

Explanation: A 'windfall' refers to an unexpected gain or advantage, often financial in nature, such as winning the lottery or receiving an inheritance. The term originates from fruit or wood that the wind blows down, which can be collected freely. This is a positive event, unlike a calamity or bad weather, which are negative. While receiving gifts is unexpected, it doesn't capture the financial aspect that 'windfall' conveys.

Q7. The word REPROACH means:

• A. Approach again
• B. Reach again
• C. Blame✓
• D. Praise

Explanation: The word 'reproach' means to express disappointment or disapproval, particularly in response to someone's behavior or actions. It is often used when someone is criticized for failing to meet certain standards or expectations. Option C, 'Blame', captures this meaning accurately. Option A, 'Approach again', and Option B, 'Reach again', incorrectly interpret the prefix 're-' to mean 'again', which is not applicable here. Option D, 'Praise', is the opposite of 'reproach', as it involves commending or positively acknowledging someone rather than criticizing them.

Q8. The word GAUNT rneans:

• A. Ill health✓
• B. Glove
• C. Stout
• D. Gravel

Explanation: The word 'gaunt' is often used to describe a person who appears very thin and bony, typically as a result of suffering from an illness, hunger, or aging. This appearance suggests a lack of health or nourishment, hence the correct answer is 'Ill health'. The other options do not relate to this context. 'Glove' is an item of clothing, 'Stout' suggests a robust physique which is the opposite of gaunt, and 'Gravel' is a type of rock material.

Q9. The word PROSCRIBE means :

• A. Say with authority
• B. Unwanted behavior
• C. Denounce✓
• D. Supportive teacher

Explanation: Denounce, which means to publicly declare something as wrong or deserving of condemnation.

Q10. To burn the candle at both end refers to :

• A. Hard work✓
• B. Face great loss
• C. Face challenge
• D. Waste money

Explanation: "Burning the candle at both ends" implies pushing oneself to the limits, working tirelessly, and expending a lot of energy. It suggests engaging in intense or excessive work without taking sufficient breaks or time for self-care. This idiom is commonly used to describe individuals who work long hours, neglect their personal well-being, and may eventually experience burnout or exhaustion.

Q11. The word LEVITY means :

• A. Impose one’s view point
• B. Serious attitude
• C. Non-serious attitude✓
• D. Enjoy frequent leave

Explanation: "Levity" refers to a lack of seriousness or lightness in manner, behavior, or attitude. It describes a tendency to treat serious matters with humor or triviality. Someone who exhibits levity often displays a light-hearted or playful approach to things that are typically regarded as serious.

Q12. Which one is the preposition ?

• A. against✓
• B. loudly
• C. so
• D. be

Explanation: A preposition is a word that typically shows the relationship between a noun or pronoun and other elements in a sentence. It indicates location, time, direction, manner, or other relationships. "Against" is a preposition. It is used to indicate a physical contact or collision between two objects or to express opposition or resistance. For example, "The book is leaning against the wall" or "They fought against injustice."

Q13. The Managing Director ……….. Staff to work had with a promise of high salary :

• A. motivates✓
• B. mitigates
• C. maneuvers
• D. minces

Explanation: The sentence suggests that the Managing Director is encouraging or inspiring the staff to work hard by promising them a high salary. The word "motivates" means to stimulate or encourage someone to take action or achieve a goal. In this context, the Managing Director is motivating the staff by offering the incentive of a higher salary.

Q14. The word INCENSE means :

• A. Make energy
• B. Alert
• C. Fool ill
• D. Encourage✓

Explanation: The word "incense" has multiple meanings depending on the context. However, one of its common meanings is to "encourage" or "inspire" someone to take action or feel enthusiastic about something. When you incense someone, you motivate or stimulate them to do or pursue something.

Q15. The word PRODIGAL means :

• A. Careful with money
• B. Wasteful with money✓
• C. Wonderful
• D. Helpful to people

Explanation: The word "prodigal" means wasteful with money or resources. It refers to someone who spends or uses money in a reckless or extravagant manner, often leading to wastefulness or extravagance.

Q16. She was ……… of the result of the interview which she attended.

• A. Reluctant
• B. Apprehensive✓
• C. Pervasive
• D. Bounced

Explanation: The word "apprehensive" means anxious or worried about something that is going to happen. In the given sentence, the person is described as being apprehensive about the result of the interview she attended. This implies that she is feeling uneasy or concerned about the outcome.

Q17. Which one is an interjection?

• A. How
• B. Hurrah✓
• C. Go
• D. Otherwise

Explanation: An interjection is a word or expression that occurs as an utterance on its own and expresses a spontaneous feeling or reaction. The correct answer is 'Hurrah', which is used to convey excitement or joy. 'How' is used as an adverb or conjunction, not an interjection. 'Go' is a verb that indicates movement, not a spontaneous expression of emotion. 'Otherwise' is an adverb used to describe alternative situations or conditions, not an interjection.

Q18. The word PREDILECTION means:

• A. Preference✓
• B. Prediction
• C. Reference
• D. Induction

Explanation: The word 'predilection' means a strong preference or liking for something. For instance, if someone has a predilection for Italian food, it means they prefer it over other cuisines. The incorrect options, 'Prediction,' 'Reference,' and 'Induction,' refer to entirely different concepts: forecasting future events, mentioning something, and a process of reasoning or initiation, respectively.

Q19. The largest demand of energy is generally fulfilled by

• A. Hydroelectric power
• B. Nuclear power
• C. Solar energy
• D. Fossil fuels✓

Explanation: Fuels that are generated very deep under the earth from the debris of plants and animals, which existed millions of years ago, are called fossil fuels. Coal, oil and natural gases are fossil fuels. Fossil fuel energy sources, such as coal, natural gas, and oil are used to meet energy demands for much of the world. Fossil fuel accounts for 84% of world’s primary consumption while hydroelectric power accounts for 6%, renewables for 5%, and nuclear power for 4%.

Q20. Which one of the bonds is broken first in glycolysis to release energy?

• A. Glycosidic✓
• B. Peptide
• C. Ester
• D. None

Explanation: Covalent bond formed between the 1st carbon atom of one monosaccharide with 4 carbon atoms of the neighboring monosaccharide unit is known as glycosidic bond which forms a polysaccharide. In the first step of glycolysis glucose is converted to glucose-6-phosphate with release of ATP(energy) with help of hexokinase enzyme. The bond broken is known as glycosidic bond.

Q21. Teeth adapted for cutting are:

• A. Canines
• B. Incisors✓
• C. Premolar
• D. Molar

Explanation: There are a total of 8 incisors found in both upper and lower jaws. Their primary function is to cut the food .There are two types of incisors – central incisors also known as aesthetic teeth which are known to maintain a pleasant smile and lateral incisors.

Q22. Mangroves are:

• A. Xerophytes
• B. Mesophytes
• C. Halophytes✓
• D. Hydrophytes

Explanation: Mangroves are tropical plants that are adapted to lose, wet soils, salt water and being periodically submerged by tides

Q23. Two chambered heart is found in:

• A. Leopardfish
• B. Fish✓
• C. Crocodile
• D. None of above

Explanation: Fishes have two chambered heart which include an auricle and an ventricle. Auricle is responsible for taking in blood from body and ventricle pumps out the blood that has entered the heart through gills and give fresh oxygen to the blood

Q24. Which of the following is a homoeothermic animal?

• A. Uromastyx
• B. Salamander
• C. Seahorse
• D. Kangaroo✓

Explanation: Homoeothermic animals are those animals which can maintain their body temperature irrespective of external temperature variation, i.e. they are warm blooded animals which include Birds, humans and other mammals.

Q25. Alternation of generations in plants is regarded a mechanism for:

• A. Achieving haploidy
• B. Promoting survival✓
• C. Producing diploidy
• D. Having no significance

Explanation: The concept of alternation of generations in plants involves a life cycle that alternates between a diploid sporophyte stage and a haploid gametophyte stage. This cycle allows plants to utilize both sexual and asexual reproduction, which is crucial for adapting to diverse environmental conditions. Sexual reproduction introduces genetic variation, while asexual reproduction enables rapid colonization. This adaptability is essential for plant survival, especially since plants are immobile and must cope with changing environments. Thus, the primary purpose of this cycle is to promote survival. Options A and C refer to haploidy and diploidy, which are components of the cycle but not its main goal. Option D is incorrect as alternation of generations is indeed significant for plant survival.

Q26. The individual with harelip shows the following conditions:

• A. Hard palate
• B. Polydactyl
• C. Cleft Palate✓
• D. Microcephaly

Explanation: Harelip is a synonymous term for Cleft Palate. A cleft palate happens if the tissue that makes up the roof of the mouth does not join together completely during pregnancy.

Q27. Receptor sensitive to smell are:

• A. Mechanical
• B. Chemical✓
• C. Photoreceptors

Explanation: Chemical receptors are sensitive to chemicals and they help differentiate and recognize taste,smell and detect changes in O2 ,CO2 and Ph.

Q28. Which hormone prepares the body for situations of stress and emergency?

• A. Adrenaline✓
• B. Non adrenaline
• C. Thyroxin
• D. Insulin

Explanation: Adrenaline triggers the body's fight-or-flight response. This reaction causes air passages to dilate to provide the muscles with the oxygen they need to either fight danger or flee. Adrenaline also triggers the blood vessels to contract to re-direct blood toward major muscle groups, including the heart and lungs.

Q29. Which of the following type of cytochromes is common in photosynthesis and respiration?

• A. Cyt “O”
• B. Cyt “a3”
• C. Cyt “b”✓
• D. Cyt “c”

Explanation: A membrane-bound cytochrome f-b complex participates in both respiratory and photosynthetic elevtron transport.

Q30. Peptide bond is formed between:

• A. Hydrogen groups of adjacent amino acids
• B. Functional group of the amino acids
• C. Carboxyl group and amino group✓
• D. Functional group and hydrogen group of adjacent amino acid

Explanation: Carboxyl or COOH– a group of one amino acid and Amine or NH3+ of another Amino acid are responsible for forming peptide bonds.

Q31. Anticodon of AUG will be:

• A. TAC
• B. UAC✓
• C. AUG
• D. CCA

Explanation: Anticodons are as follow:A = U( in case of RNA)A=T ( in case of DNA)C=G( same in both cases)

Q32. Which of these is a fresh water sponge?

• A. Sycon
• B. Leucosolenia
• C. Spongilla✓
• D. Euplectella

Explanation: Spongilla is the only freshwater sponge among the options provided. It is typically found in clean lakes and slow-moving streams. In contrast, Sycon, Leucosolenia, and Euplectella are marine sponges that inhabit different types of saltwater environments. Sycon and Leucosolenia are commonly found in shallower marine waters, whereas Euplectella, known as the glass sponge, is often located in the deep ocean.

Q33. In earthworm, mucin & enzyme are produced by:

• A. Intestinal sac
• B. Typhlosole
• C. Oesophagus
• D. Pharyngeal mass✓

Explanation: The pharyngeal gland is made of chromophil cells, which produce saliva containing the proteolytic enzyme; protease, and mucin which convert a protein into amino acids and make the food soft respectively.

Q34. Food is renewable resource due to:

• A. Mechanical forming
• B. Improved crop varieties
• C. Continuous photosynthesis✓
• D. Pest control

Explanation: Food is considered a renewable resource primarily because of continuous photosynthesis, which allows plants to convert sunlight into energy, produce food, and support life on Earth. This natural process ensures that plants, which form the base of most food chains, can constantly produce food. Options A, B, and D refer to techniques and methods that enhance food production but do not inherently make food renewable. Mechanical forming prepares land for cultivation, improved crop varieties increase productivity, and pest control protects crops, but none of these address the natural regenerative process of photosynthesis.

Q35. The term bivalent means:

• A. Two chromatids
• B. Two chromosomes✓
• C. Six chromatids
• D. Four chromosomes

Explanation: The term bivalent refers to a specific structure that forms during meiosis, the process of cell division that produces gametes (sex cells). Bivalents are formed when two homologous chromosomes pair up and align side by side .Bivalent chromosomes, or bivalents, are the paired homologous chromosomes that form during meiosis I. Each chromosome in a bivalent is a replicated structure consisting of two sister chromatids, making a bivalent a unit containing four DNA molecules (two homologous chromosomes, each with two sister chromatids) that are held together by a synaptonemal complex. This pairing is crucial for the proper alignment and segregation of chromosomes in the first meiotic division. Let's go through each option and explain them:Two chromatids: Chromatids are duplicated copies of a chromosome that are joined together by a centromere. During meiosis, chromatids pair up to form bivalents, so the statement is partially correct. However, it's important to note that a bivalent consists of two homologous chromosomes, each composed of two chromatids.Two chromosomes: This is the correct option. A bivalent consists of two homologous chromosomes, one from each parent. Each chromosome is composed of two chromatids. The pairing and alignment of these homologous chromosomes during meiosis are crucial for genetic recombination and the exchange of genetic material.Six chromatids: This option is incorrect. A bivalent consists of two homologous chromosomes, and each chromosome has two chromatids. So, the total number of chromatids in a bivalent is four, not six.Four chromosomes: This option is incorrect. A bivalent involves the pairing of two homologous chromosomes, one from each parent. So, there are only two chromosomes involved in the formation of a bivalent.Therefore, the correct option is B: Two chromosomes.

Q36. Class filicinae belongs to "phylum"

• A. Tracheophyta✓
• B. Bryophyte
• C. Thallophyta
• D. Embryophyta

Explanation: Class filicinae comes under vascular plants or tracheophyta.

Q37. Which one among the following is NOT available at a vegetable shop?

• A. Capsicum annum
• B. Pisum Sativum
• C. Triticum Aestivom✓

Explanation: Triticum Aestivom is the common wheat.

Q38. What happens to oxygen in the electron transport chain?

• A. It is reduced to water✓
• B. It is converted to gas
• C. It is used as an electron carrier
• D. It supplies energy to produce ATP

Explanation: Oxygen plays a crucial role in the electron transport chain as the final electron acceptor. It combines with electrons and protons at the end of the chain to form water, a process known as reduction. This is essential for maintaining the flow of electrons through the chain, which in turn helps establish the proton gradient necessary for ATP production. The other options are incorrect because they either misrepresent oxygen's role in the electron transport chain or attribute functions to it that it does not perform.

Q39. Which animal posesses an open circularity system?

• A. Amoeba
• B. Earthworms
• C. Grasshoppers✓
• D. Man

Explanation: Grasshoppers have an open circulatory system with a heart. Their blood just bathes over their cells.

Q40. Which of the following compounds has no double bond?

• A. Phospholipids
• B. Cellulose✓
• C. Cholesterol
• D. Vitamin A

Explanation: Cellulose has no double bonds. Cholesterol and Retinol (vitamin A) have double bonds.

Q41. Calvin cycle takes place within:

• A. Stoma of chloroplasts✓
• B. Granum of the chloroplast
• C. Cytoplasm of the cell
• D. ....

Explanation: Unlike the light reactions, which take place in the thylakoid membrane, the reactions of the Calvin cycle take place in the stroma, the inner space of chloroplasts.

Q42. Which enzyme helps in the digestion of carbohydrate?

• A. Ptyalin✓
• B. Pepsin
• C. Diastase
• D. option missing

Explanation: Ptyalin aids in the digestion of starch in the mouth. Diastase breaks down starch into maltose in germinating seeds.

Q43. Wings of a bird and fore limbs of a man are:

• A. Homologous✓
• B. Analogous
• C. Acquired
• D. Vestigial

Explanation: These are the organs that have similar anatomical structures but perform different functions. Wings and forelimbs develop as a result of divergent evolution.

Q44. The association in which an organism gets advantage and the other suffers is called:

• A. Symbiosis
• B. Parasitism✓
• C. Predation
• D. Mutualism

Explanation: A parasitic relationship is one in which one organism, the parasite, lives off of another organism, the host, harming it and possibly causing death.

Q45. The modern horse is called:

• A. Equus✓
• B. Eohippus
• C. Mesohippus
• D. Merychippus

Explanation: The modern horse is called Equus caballus.

Q46. If we cover the lateral sides of the Gross-hopper with wax. The system most likely to be affected will be

• A. Digestive
• B. Circulatory
• C. Respiratory✓
• D. Excretory

Explanation: Instead of nostrils, grasshoppers breathe through openings in the thorax and abdomen called spiracles. When covered with wax, gaseous exchange is greatly reduced.

Q47. Which of the following does not bring erosion of soil?

• A. Carolers forming
• B. Extensive ploughing
• C. Moderate grazing✓
• D. Heavy grazing

Explanation: Moderate grazing refers to controlled or balanced grazing practices where the number of livestock and their grazing duration are managed in a sustainable manner. It involves maintaining a healthy vegetation cover and avoiding overgrazing. This practice can actually be beneficial for the soil and ecosystem as it helps in maintaining biodiversity, nutrient cycling, and organic matter accumulation.

Q48. The human sacrum consists of how many vertebrae?

• A. Two
• B. Three
• C. Four
• D. Five✓

Explanation: The sacrum is a large, triangular bone located at the base of the vertebral column, between the lumbar vertebrae and the coccyx. It is formed by the fusion of five separate sacral vertebrae (S1 to S5). These individual vertebrae fuse together during development to form a single bone called the sacrum.

Q49. Which of the following meristem is responsible for wood formation in plants :

• A. Lateral meristem✓
• B. Apical meristem
• C. Intercalary
• D. None

Explanation: The meristem responsible for wood formation in plants is the lateral meristem, specifically the vascular cambium and the cork cambium. Lateral meristems are responsible for the secondary growth of plants, which involves the thickening of stems and roots. The vascular cambium is a type of lateral meristem located between the xylem and phloem tissues in the stems and roots of woody plants. It produces new xylem cells towards the center of the stem, contributing to the growth of wood. The cork cambium, another lateral meristem, produces the outer bark of the stem, providing protection to the underlying tissues.

Q50. Bones are held together of the joints by :

• A. Tendons
• B. Smooth muscles
• C. Ligaments✓
• D. Nerves

Explanation: Bones are held together at joints by ligaments. Ligaments are fibrous connective tissues that connect bones to other bones, providing stability and strength to the joint. They play a crucial role in holding the bones in proper alignment and preventing excessive movement or dislocation.

Q51. Raphanus sativus belongs to family :

• A. Poaceae
• B. Fabaceae
• C. Brassicaceae✓

Explanation: Raphanus sativus, commonly known as radish, belongs to the family Brassicaceae (also known as Cruciferae). Brassicaceae is a family of flowering plants that includes many well-known vegetables and herbs, such as cabbage, broccoli, cauliflower, kale, and mustard.

Q52. The developing embryo is protected against the physical trauma by :

• A. Pericardial fluid
• B. Allantoic fluid
• C. Amniotic fluid✓
• D. All of these

Explanation: Amniotic fluid plays a crucial role in protecting the developing embryo/fetus against physical trauma. It is a liquid that surrounds the embryo/fetus within the amniotic sac, which is formed by the amnion membrane. The amniotic fluid acts as a cushion, providing a protective barrier and absorbing shocks or impacts that may occur during movement or external forces.

Q53. If red and white color flowers in mirabulus jalapa are crossed, the F1 generation will show:

• A. All red
• B. All white
• C. All pink
• D. 1, red, 2, pink & 1 white ratio✓

Explanation: When red and white color flowers in Mirabilis jalapa (Four O'Clock Flower) are crossed, the F1 generation will typically display an intermediate phenotype, resulting in pink-colored flowers. This is due to incomplete dominance or blending inheritance, where neither the red nor white color allele is completely dominant over the other. In this case, the red color is typically controlled by the presence of a dominant allele (R), while the white color is controlled by a recessive allele (r). When the red and white flowers are crossed, the F1 generation will inherit one copy of the dominant red allele (R) from one parent and one copy of the recessive white allele (r) from the other parent. As a result, the F1 plants will have a heterozygous genotype (Rr) and exhibit an intermediate phenotype, which is pink-colored flowers.

Q54. The growth of pollen tube through style to the ovary is type of movement called :

• A. Geotropism
• B. Chemotropism
• C. Chemotropism✓
• D. Phototropism

Explanation: The growth of a pollen tube through the style to the ovary is a type of movement known as chemotropism. Chemotropism is the directional growth or movement of an organism or part of an organism in response to a chemical stimulus. In this case, the pollen tube is guided by chemical signals released by the ovary, which attract and guide the tube towards the ovule for fertilization.

Q55. Which of the following expel imperfectly developed embryo out the body :

• A. Prototherians
• B. Eutherians
• C. Metatherian✓
• D. All of above

Explanation: Metatherians, also known as marsupials, are a group of mammals that give birth to relatively undeveloped embryos. These embryos are then transferred to a pouch or marsupium, where they continue their development outside the mother's body. This process is known as marsupial reproduction.

Q56. Each organism has a definite functional position different from either organisms of the locally is called :

• A. Community
• B. Niche✓
• C. Habitat
• D. Species

Explanation: In ecology, a niche refers to the specific role or position that an organism occupies within an ecosystem. It includes the range of conditions and resources that the organism requires for survival and reproduction, as well as its interactions with other organisms in the community. The niche of an organism is defined by its unique combination of habitat requirements, behavior, and ecological interactions.

Q57. If the sequence of one strand of DNA is ATGCTC, the sequence of the other strand would be :

• A. CACGTC
• B. TAGCATG
• C. TACGAG✓
• D. GACGTG

Explanation: In DNA, the base pairs are complementary to each other. Adenine (A) always pairs with thymine (T), and guanine (G) always pairs with cytosine (C). Therefore, if one strand of DNA has the sequence ATGCTC, the other strand will have the complementary sequence i.e., TACGAG.

Q58. Which of the following physiological phenomenon is responsible of guttation :

• A. Capillary rise of water
• B. Root pressure✓
• C. Tensile strength
• D. All of these

Explanation: Guttation is the process by which plants excrete excess water in the form of droplets through specialized structures called hydathodes. It typically occurs during the night or early morning when the soil moisture is high and the transpiration rate is low.

Q59. The critical day length of Hyoscyamus for flowering is :

• A. 15.5 hours✓
• B. 9 hours
• C. 11 hours
• D. 13 hours

Explanation: Hyoscyamus, like many plants, has a specific photoperiod requirement known as the critical day length, which is the minimum daylight hours necessary to trigger flowering. For Hyoscyamus, this is 15.5 hours. If the day length is less, the plant will not flower. The other options provide shorter day lengths, which are insufficient to meet the plant's photoperiodic needs. Understanding photoperiodism is crucial in botany, as it significantly influences plant development and reproductive cycles.

Q60. Two individuals formed when two eggs fertilized of the same time results in twins that are genetically different are:

• A. Identical twins
• B. Siames twins
• C. Fraternal twins✓
• D. Double twins

Explanation: When a woman’s ovary releases two eggs which are fertilized by two different sperms, it results in the formation of fraternal twins. Fraternal twins or triplets or quadruplets come from different eggs which are fertilized by different sperms therefore also called dizygotic or multiple zygotic. Fraternal foetuses come from separate placentas and amniotic sacs. They can have different sexes and different blood types and may look very different from each other

Q61. Which of the following group of animals run very fast?

• A. Digitgrade✓
• B. Unguligrade
• C. Plantigrade

Explanation: A digitgrade is defined as those group of mammals that solely walk on their toes only and not touching the ground with their heels for example dogs, cats etc. They are faster than any other group of animals. The word digit comes from a latin word “digitus” meaning toes, fingers while the word “grade” means walking.

Q62. "The open water zone away from shore to the depth of affective light penetration and occupied by phylopplankion Iike green algae euglena etc." which of the following regions of fresh water has all these properties?

• A. Littoral
• B. Limnetic✓
• C. Profundal
• D. Both "a" and "b"

Explanation: It is the open water zone away from the shore and it extends up to the effective light penetration level. The limnetic zone is well-lighted (like the littoral zone) and is dominated by plankton, both phytoplankton and zooplankton. Plankton are small organisms that play a crucial role in the food chain.

Q63. When an anopheles of mosquito bites a healthy person if injects:

• A. Merozoites
• B. Sporozoites✓
• C. Gametocytes
• D. Oocytes

Explanation: The well-matured sporozoites are injected into the human host through the saliva of an Anopheles mosquito when it bites to feed on the blood. When mosquitoes bite, they inject a tiny amount of their saliva (less than a microliter), which contains a specialized, potent cocktail of molecules that numb the pain of the bite and stop the blood from clotting.

Q64. All of the following are nematodes except:

• A. Ascaris
• B. Neresis✓
• C. Trichinella
• D. Guinea worm

Explanation: Nematodes are free living or parasite, and live in soil, roots, human and animal intestine and muscles. Most roundworms are less than five cm in length and many are microscopic but some parasitic roundworms are more than one meter in length.

Q65. Daphnia belongs to the class:

• A. Insecta
• B. Arachnida
• C. Myriapoda
• D. Crustacean✓

Explanation: Crustaceans form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group can be treated as a subphylum under the clade Mandibulata. A crustacean has the following features: • a segmented body with a hard exterior (known as an exoskeleton) • jointed limbs, each often with two branches (termed biramous) • two pairs of antennae. • gills.

Q66. In bryophytes sterile hair are produced seen sex organs to keep them:

• A. Dry
• B. Wet✓
• C. Warm
• D. Covered

Explanation: Bryophytes have wet sterile hairs in between the sex organs to keep them protected from drying condition and for protection of reproductive cells.

Q67. Gas·evolved in bioconversion of solid waste is:

• A. Methane✓
• B. Sulpher dioxide
• C. Nitrogen dioxide
• D. Ethane

Explanation: Solid wastes are biologically converted into value added products by physiological action of microorganisms. These processes occur under controlled environmental condition. It could be in the form of submerged fermentation or as solid-state fermentation technology. The gas released during this conversion is methane and carbon dioxide. Usually, carbon dioxide is released during aerobic conversion of solid waste while methane is released during anaerobic conversion of solid waste.

Q68. Crop rotation leads to:

• A. Increase in the soil nutrient✓
• B. More aeration of soil
• C. Soil fertility
• D. ....

Explanation: Crop rotation helps return nutrients to the soil without synthetic inputs. The practice also works to interrupt pest and disease cycles, improve soil health by increasing biomass from different crops' root structures, and increase biodiversity on the farm.

Q69. Which of one of the following characteristics in man is controlled by a recessive gone?

• A. Tongue rolling
• B. Diabetes
• C. Skin colour
• D. Eye colour✓

Explanation: This mcq can only be solved by elimination trick. Tongue rolling is controlled by dominant trait while skin colour is a polygenic trait and exhibits intermediate phenotype due to co-dominance. This rules out option A and D. Diabetes is not usually linked with genetic factors and if it is even linked it is only autosomal dominant. This makes eye colour the best option in which blue eye colour is controlled by recessive gene.

Q70. The major and immediate nitrogenous waste product of protein metabolism is:

• A. Urea
• B. Uric acid
• C. Creatinine
• D. Ammonia✓

Explanation: Urea is the major and immediate nitrogenous waste product of protein metabolism in humans and most mammals. It is produced in the liver through the urea cycle, which converts toxic ammonia into urea, a less toxic compound, before it is excreted in urine. Uric acid, creatinine, and ammonia are also nitrogenous waste products but arise from different metabolic processes or are less prevalent as a direct result of protein metabolism.

Q71. Phages viruses are usually abundant in the intestine of man and animals because.

• A. Abundant bacteria are present✓
• B. Abundant water is present
• C. Abundant nutrients are present
• D. They can only live at human body temperature

Explanation: Phages can translocate through the mucosa to lymph and internal organs and play a role as regulators of the bacterial population in the gut. Increasing abundance of phages in the gut mucosa may reduce colonization by bacteria. Moreover, phages may have an immunomodulatory role in the immune response in the human gut. Bacteriophages play important roles in regulating the intestinal human microbiota composition, dynamics, and homeostasis, and characterizing their bacterial hosts is needed to understand their impact.

Q72. In a woody-plant the·number of structures on ion sin cell has to cross to reach the adjunction cell is:

• A. 3✓
• B. 5
• C. 6
• D. 7

Explanation: The ion crosses three main structures when moving from one cell to an adjacent cell in a woody plant:Middle Lamella: This is the pectin-rich layer which cements the cell walls of two adjoining plant cells together.Primary Cell Wall: This is the outermost layer of the cell wall, which is flexible and allows for cell growth.Secondary Cell Wall: This is a thicker and more rigid structure found beneath the primary cell wall, common in woody plants to provide strength and support.These structures are essential for providing support and protection, while also facilitating the movement of ions via channel proteins, as the cell membrane itself is non-polar and ions are polar. Options B, C, and D include additional or irrelevant structures that are not necessary for ion movement between adjacent cells.

Q73. Which of the following is Not in the pancreatic juice?

• A. Amylase
• B. Lipase
• C. Trypsinogen
• D. Insulin✓

Explanation: Option D is correct as pancreas is a heterocrine gland which also produces hormone named as insulin and glucagon which are produced by the beta cells and alpha cells respectively. The hormone insulin functions to decrease the glucose level of blood while the hormone glucagon works to increase the glucose level. Thus the hormones work contrary to each other. Read the following paragraph to have a better understanding of pancreas. The enzymatic component of the pancreatic juice is produced by the acini cells of the pancreas and is important for the digestion of all major classes of food. Without the enzymes produced by the pancreas, lipids, proteins, and carbohydrates are not adequately digested. The proteolytic pancreatic enzymes, which digest proteins, are secreted in inactive forms, whereas many of the other enzymes are secreted in active form. The major proteolytic enzymes are trypsin, chymotrypsin, and carboxypeptidase. They are secreted in their inactive forms as trypsinogen, chymotrypsinogen, and procarboxypeptidase and are activated by the removal of certain peptides from the larger precursor proteins. If these were produced in their active forms, they would digest the tissues producing them. Trypsinogen is activated by the proteolytic enzyme enterokinase (meaning, intestinal enzyme), which is an enzyme attached to the brush border (microvilli) of the small intestine. Trypsin then activates more trypsinogen, as well as chymotrypsinogen and procarboxypeptidase. Pancreatic juice also contains pancreatic amylase, which continues the polysaccharide digestion that was initiated in the oral cavity. In addition, pancreatic juice contains a group of lipid digesting enzymes called pancreatic lipases, which break down lipids into free fatty acids, glycerides, cholesterol, and other components. Enzymes that reduce DNA and ribonucleic acid to their component nucleotides, deoxyribonucleases and ribonucleases, respectively are also present in pancreatic juice.

Q74. An atom has a net charge of -1 it has 18 electron and 20 neutron its mass number is

• A. 37✓
• B. 32
• C. 35
• D. 20

Explanation: Atom A has 18 electrons with net charge of -1 which means it gained one electron. Hence number of proton= number of electron - atomic charge = 18 - 1 = 17 The number of proton will be 17. Now Mass number=number of proton + number of neutron Mass number = 17+20= 37

Q75. Conc:H2SO4 is added to a mixture of K2CR2O7 and metal chloride is solid scale. Brown vapors are formed. Which one is the correct formula?

• A. CrOCl2
• B. COCl2
• C. CrO2Cl2✓
• D. CrCl6

Explanation: When a mixture of K2CR2O7 and metal chloride is added in warm conc: H2SO4 Chromyl chloride ( CrO2Cl2) which forms a deep reddish brown color vapors These vapors when passed into NaOH solution gives a yellow solution of Na2CrO4. 6H2SO4 + K2CR2O7 + 4NaCl —-> 2KHSO4 + 4NaHSO4 + 2CrO2Cl2 +3 H20 CrO2Cl2 + 2NaOH → Na2CrO4 + 2HCL (YELLOW SOLUTION)

Q76. The ionization energy of a hydrogen atom is 13.6 ev. The ionization potential required will be:

• A. 4.9 volt
• B. 8.5 * 10-10 volt
• C. 3.4 volt
• D. 13.6 volt✓

Explanation: The ionization energy of a hydrogen atom is the energy required to remove an electron from the atom. It is given as 13.6 electron volts (eV). When determining the ionization potential, which is essentially the energy needed per electron to remove it from the influence of the nucleus, the same value (13.6 eV) applies. Thus, the ionization potential, when expressed in volts, is also 13.6 volts.Option A (4.9 volts) is unrelated to the ionization energy of hydrogen. Option B (8.5 * 10-10 volts) is incorrectly expressed in scientific notation and is far too small. Option C (3.4 volts) may be relevant to transitions between specific energy levels in hydrogen but is not the ionization potential. Therefore, only Option D correctly matches the ionization energy with the ionization potential at 13.6 volts.

Q77. Which one of the following is not correct:

• A. Xe is the most reactive among rare gasses
• B. He is an inert gas
• C. Randon is obtained from decay of radium
• D. The most abundant rare gas found in atmosphere is He✓

Explanation: The most abundant rare gas found in the atmosphere is Argon not Helium.

Q78. Metallic carbide on treatment with water gives a colorless gas which burns readily in air and gives a white precipitate with AgNO3 + NaOH the gas is

• A. CH4
• B. C2H2✓
• C. C2H4
• D. C2H6

Explanation: Metallic carbide/Calcium Carbide: CaC2 Calcium carbide on hydration gives acetylene. Which on reaction with sodium hydroxide and silver nitrate produces white ppt. Solution: Reacting metallic carbide with water: CaC2 + 2H2O —--> Ca(OH)2 + C2H2 The gas C2H2 is acetylene Reacting acetylene with air/O2 C2H2 + 5/2O2 —-> 2CO2 + H2O CH≡ CH + 2[Ag(NH3)2]NO3 —> Ag−C≡ C−Ag + 2NH3 +2 NH4NO3

Q79. Which product is obtained when methyl magnesium chloride react with ammonia:

• A. Methane✓
• B. Methyl amine
• C. Ethyl amine
• D. Methyl chloride

Explanation: CH3-Mg-Cl +NH3 —--------> CH4 + NH2MgCl Grignard reagent/methyl magnesium chloride is basic in nature so it will accept H+ from ammonia and form methane.

Q80. The total energy of a hydrogen atom in its ground state is:

• A. Zero
• B. Negative✓
• C. Positive
• D. None of the above

Explanation: The energy of a hydrogen atom in its ground state is negative, approximately -13.6 eV. This negative value indicates that the electron is bound to the nucleus, requiring energy input to free it. The Schrödinger equation and the Bohr model both support this result, with the ground state corresponding to the principal quantum number n = 1. The other options are incorrect: a zero or positive energy would suggest the electron is not bound to the nucleus, contrary to the nature of a ground state electron.

Q81. Which of the following cannot be displaced from their salt solution by copper?

• A. Ag
• B. AU
• C. Pt
• D. Zn✓

Explanation: A more reactive metal can displace a less reactive metal from its salt in an aqueous solution. Since copper is less reactive than zinc, therefore it cannot displace Zinc from its salt solution. But copper is more reactive than mercury, silver and gold hence can replace than from their respective salt solutions.

Q82. For atomic numbers given below , which pair of elements will have the same chemical properties ?

• A. 13,22
• B. 3,11✓
• C. 4,24
• D. 2,4

Explanation: Elements belonging to the same group have the same chemical properties. The 13th element in the periodic table is aluminum and 22nd is titanium belonging to different groups and periods.Hence they have different chemical properties. The 3rd element in the periodic table is lithium and the 11th is sodium, both belonging to 1st group/Alkali metals. Hence both have similar chemical properties. The 4th element in the periodic table is beryllium and the 24th is chromium, both belonging to different periods and groups.Hence they have different chemical properties. The 2nd element in the periodic table is helium and the 4th is beryllium, both belonging to different periods and groups.Hence they have different chemical properties.

Q83. 74g of calcium hydroxide will yield OH– ions:

• A. 17g
• B. 34g✓
• C. 51g
• D. 40g

Explanation: mole= given mass in gram/molar mass Mole of calcium hydroxide = 74/74 = 1 mole OH- mass in Ca(OH–)2 = (17)2 = 34 OH– ions = 1 x 34 = 34g answer!

Q84. Which of the following pairs have the same electronic structure?

• A. Ar & Cl–1✓
• B. Ca & Ar
• C. Mg & Na
• D. Ag & Sn

Explanation: Ar = 1s22s22p63s23p6 Cl– = 1s22s22p63s23p6 (doing for 18 electron instead of 17 because it gained one electron/anion)

Q85. The oxidation number of chlorine in Ca(ClO3)2 is:

• A. -1
• B. +3
• C. +5✓
• D. -6

Explanation: In the compound Ca(ClO3)2, calcium has an oxidation state of +2, being a Group 2 metal. Each ClO3- ion must balance to -1 overall charge. Oxygen typically has an oxidation state of -2. Since there are three oxygen atoms, their total contribution is -6. To balance this to -1 for each ClO3-, chlorine must have an oxidation state of +5. Therefore, the oxidation number of chlorine in Ca(ClO3)2 is +5.Options -1 and -6 are incorrect as they do not balance the charges correctly. Option +3 does not account for the full negative contribution of the oxygen atoms.

Q86. lf glass manufacturing process annealing is done for the prevention of:

• A. Air bubbles
• B. Impurities
• C. Strain✓
• D. Shining

Explanation: The process of annealing glass is done to reduce internal stresses or strain which could otherwise lead to cracking.

Q87. lf 28.0g nitrogen gas is reacted with 8.0g of hydrogen gas to form Ammonia, the limiting reactant among the two will be:

• A. N2✓
• B. H2
• C. Both a & b
• D. None of them

Explanation: The balanced chemical equation for the formation of ammonia (NH3) is:N2 + 3H2 → 2NH3You start with 28.0 g of N2 and 8.0 g of H2. The molar mass of N2 is 28.0 g/mol, so you have 1 mole of N2. The molar mass of H2 is 2.0 g/mol, so you have 4 moles of H2.According to the balanced equation, 1 mole of N2 requires 3 moles of H2 to fully react. Since you have only 1 mole of N2 and 4 moles of H2, N2 will run out first, making it the limiting reactant. Therefore, the correct answer is Option A: N2.Option B is incorrect because there is excess H2 present. Option C is incorrect because only one reactant can be limiting. Option D is incorrect because there must be a limiting reactant in this scenario.

Q88. The unit of K.c or the system N2O4 ⇋ 2NO2 is :

• A. Dimension (1.0 with no unit)
• B. Mole dm3
• C. Mole dm-3✓
• D. Mole2 dm3

Explanation: M2/M = mol dm-3

Q89. What is the trade name of titraflora ethylene polymer?

• A. Polystoene
• B. Backlite
• C. Nylone
• D. Teflone✓

Explanation: Tetrafluoroethylene is commonly known as Teflon.

Q90. Which one of the following does not have +7 oxidation ....

• A. F✓
• B. Cl
• C. Br
• D. I

Explanation: Fluorine is unique among the halogens as it is the most electronegative element, and it only forms compounds where it can achieve a -1 oxidation state. This is due to its high electronegativity and small atomic size, which makes it unfavorable to lose electrons to achieve a positive oxidation state.In contrast, chlorine, bromine, and iodine can all exhibit a +7 oxidation state in certain compounds. Chlorine does this in perchlorates, bromine in bromates, and iodine in periodates.

Q91. The sum of the number of protons and the number of neutrons present in the nucleus of an atom is known as:

• A. Charge number
• B. Mass number✓
• C. Atomic number
• D. Magic number

Explanation: Mass number is the sum of protons and neutrons in the nucleus.

Q92. What type of intermolecular altractive force are present in CO2?

• A. Hydrogen bonding
• B. Dipole-dipole interaction
• C. London forces✓
• D. Covalent bounding

Explanation: London forces are caused by movement of electrons leading to instantaneous dipoles. It is the only force present in CO2 hence the low boiling point.Atomic number is the number of protons in an atom.

Q93. Warmer water at 40C is:

• A. Lighter
• B. Highest
• C. Heavier
• D. Heaviest✓

Explanation: Water has the highest density at 4 degree C as the cage-like structure which forms when water freezes starts breaking. Volume decreases hence water becomes more dense or heavier.

Q94. 10 L of Cl2 gas reacts with 40L of H2 gas under same condiitions of temperature and pressure. How much volume of HCl should be produced?

• A. 40L
• B. 30L
• C. 20L✓
• D. 10L

Explanation: The balanced chemical equation 𝐻2 + 𝐶𝑙2 = 2𝐻𝐶𝑙 shows that each mole of Cl2 produces two moles of HCl. At constant temperature and pressure, volumes of gases are proportional to moles. Thus, 10L of Cl2 will react with 10L of H2 to produce 20L of HCl. Cl2 is the limiting reactant, and the excess H2 remains unreacted. Option C is correct; other options either misinterpret the stoichiometry or the limiting reactant concept.

Q95. In the discharge tube emission the cathode rays requires:

• A. A: Low potential and low pressure
• B. B: Low potential and high pressure
• C. C: High potential and high pressure
• D. D: High potential and low pressure✓

Explanation: In a discharge tube, cathode rays are produced when electrons are emitted from the cathode and accelerated towards the anode. For this to occur efficiently, a high potential difference is necessary to provide the electrons with sufficient energy. Additionally, low pressure is critical because it reduces the number of gas molecules in the tube, allowing the electrons to travel freely without colliding with gas particles. **Option A** (Low potential and low pressure) is incorrect because insufficient potential fails to accelerate the electrons adequately, and low pressure can hinder the process of ionization. **Option B** (Low potential and high pressure) is also incorrect as high pressure would impede the movement of electrons, and low potential does not provide the necessary energy for cathode ray production. **Option C** (High potential and high pressure) is wrong because, although high potential is favorable, high pressure creates a barrier to electron travel, thus preventing effective cathode ray emission. Therefore, **Option D** (High potential and low pressure) is the only configuration that allows for effective cathode ray emission.

Q96. Which one of the following is not derivative of organic acid?

• A. Ester
• B. Amide
• C. Anhydride
• D. Amine✓

Explanation: Amines are derivatives of ammonia where H is replaced by one or more alkyl or aryl groups.

Q97. Dehydrahalogenation·of alkyl halide·is carried with:

• A. Alcoholic KOH✓
• B. Aqueous KOH
• C. Aqueous NaOH
• D. Alcoholic HaOH

Explanation: The suitable reagent used for dehydrohalogenation of alkyl halides would be alcoholic KOH. Here are some examples.

Q98. When treated with ammonical cuprous chloride, which of the following forms copper derivates?

• A. C2H6
• B. C2H4
• C. C2H2✓
• D. C6H6

Explanation: Only alkynes can perform this reaction. 2[Cu(NH)3]OH + HC≡CH → Cu−C≡C−Cu + 4NH3 + 2H2O copper acetylide Red ppt.

Q99. Baron is prepared by heating B2O3 with:

• A. Potassium powder✓
• B. Bleaching Powder
• C. Carbon powder
• D. Baking powder

Explanation: Explanation is given as image.

Q100. Consider the following.general reaction lA .. lB → Products rate of this reaction is expressed asRate = K[A][B]' the correct order of reaction and molecularity is:

• A. 2:2✓
• B. 2:3
• C. 3:2
• D. 3:3

Explanation: The correct answer is 2:2. The order of a reaction is determined by the sum of the exponents of the concentration terms in its rate law. In this case, Rate = K[A][B] implies an order of 1 with respect to A and 1 with respect to B, giving an overall order of 2. Molecularity refers to the number of reactant molecules involved in an elementary reaction step. Since the reaction involves two molecules (A and B), the molecularity is 2. Other options are incorrect because they either misrepresent the number of reactant molecules involved or miscalculate the reaction order.

Q101. Consider the reaction : 2SO2 + O2 …………. 2SO3 + Heat will be maximum if :

• A. Both pressure and temperature are increased
• B. Both pressure and temperature are decreased
• C. Temperature is decreased and pressure is increased✓
• D. Temperature is increased and pressure is increased

Explanation: The reaction 2SO2 + O2 → 2SO3 is exothermic, releasing heat. According to Le Chatelier's principle, increasing pressure shifts the equilibrium towards the side with fewer moles of gas, which is the forward reaction. Increasing temperature enhances the reaction rate by providing more energy to overcome activation energy. Therefore, the reaction rate and product formation are maximized when both pressure and temperature are increased.Options A and C, although they involve increasing pressure, do not involve increasing temperature, which is necessary to maximize the reaction rate. Option B decreases both pressure and temperature, which is counterproductive to both reaction rate and product formation.

Q102. In one molal aqueous solution of C2H3OH the mole fraction of C2H5OH is :

• A. 0.1✓
• B. 0.9
• C. 0.0177
• D. 1.0

Explanation: Explanation for this question will be added soon.

Q103. Which one of the following is electron deficient compounds :

• A. NH3
• B. PH3
• C. PCL3
• D. BCL3✓

Explanation: Electron-deficient compounds are those that have fewer electrons than what would be expected based on the octet rule or the number of valence electrons available. These compounds often involve elements from groups 2 and 13 of the periodic table, as they tend to form compounds with incomplete valence shells.

Q104. In which period is the most electronegative element found :

• A. 1
• B. 2✓
• C. 3
• D. 4

Explanation: The most electronegative elements are found in Period 2 of the periodic table. Electronegativity is the tendency of an atom to attract electrons towards itself when it is involved in a chemical bond. In general, electronegativity tends to increase across a period from left to right in the periodic table. In Period 2, the elements from lithium (Li) to neon (Ne) are located. Fluorine (F) is the most electronegative element in this period, followed by oxygen (O). These elements have high electronegativity values because they have a strong attraction for electrons due to their atomic structure.

Q105. The formation of PVC from vinyl chloride is an example of :

• A. Substitution reaction
• B. Addition polymerization✓
• C. Condensation polymerization
• D. Condensation reaction

Explanation: The formation of PVC (Polyvinyl Chloride) from vinyl chloride is an example of addition polymerization. In addition polymerization, monomers join together to form a polymer without the elimination of any byproducts. It involves the repetitive addition of monomer units to form a long-chain polymer. In the case of PVC, vinyl chloride monomers undergo addition polymerization, where the carbon-carbon double bond in vinyl chloride opens up, and the monomers link together to form a long polymer chain of polyvinyl chloride.

Q106. The type of intermolecular forces (forces between the particles) present in solid mercury is:

• A. Covalent bonds
• B. Ionic bonds
• C. Metallic bonds✓
• D. H-bonds

Explanation: Solid mercury, or simply mercury (Hg) in its solid state, is an example of a metal. In metals, the bonding between atoms is primarily due to metallic bonds. Metallic bonds occur between metal atoms and are characterized by the delocalization of electrons. In a metallic bond, the valence electrons of the metal atoms are loosely held and can move freely throughout the solid lattice, creating a "sea" of delocalized electrons. This electron delocalization gives rise to several unique properties of metals, such as high electrical and thermal conductivity and malleability.

Q107. Which one of the following contains the greatest number of atoms :

• A. 4g of hydrogen
• B. 4g of magnesium
• C. 71 g of chlorine✓
• D. 127 g of iodine

Explanation: Now let's calculate the number of atoms for each substance: a) 4g of hydrogen (H): 4 moles of hydrogen × (6.022 × 1023 atoms/mol) = 2.409 × 1024 atoms of hydrogen b) 4g of magnesium (Mg): 0.165 moles of magnesium × (6.022 × 1023 atoms/mol) = 9.923 × 1022 atoms of magnesium c) 71g of chlorine (Cl): 2 moles of chlorine × (6.022 × 1023 atoms/mol) = 1.204 × 1024 atoms of chlorine d) 127g of iodine (I): 1 mole of iodine × (6.022 × 1023 atoms/mol) = 6.022 × 1023 atoms of iodine

Q108. Substances dissolved in water react better because :

• A. Water brings them close
• B. Water helps them in bonding
• C. Water dissolve them in ions✓
• D. Water reacts with them

Explanation: When substances dissolve in water, they often undergo a process called hydration, where the water molecules surround and separate the individual particles of the substance, resulting in the formation of ions. This process is known as dissociation or ionization. Water has a polar molecular structure, meaning it has a slightly positive charge on one end (hydrogen) and a slightly negative charge on the other end (oxygen). This polarity allows water molecules to interact with charged particles (ions) and polar molecules by forming hydrogen bonds.

Q109. The catalyst used in the contact process is easily poisoned by :

• A. Nitrous oxide
• B. Carbon oxide
• C. Arsenic oxide✓
• D. Nitrogen oxide

Explanation: In the contact process, the catalyst used is typically a combination of vanadium(V) oxide (V2O5) or platinum (Pt) supported on a substrate such as silica (SiO2). This catalyst is responsible for promoting the oxidation of sulfur dioxide (SO2) to sulfur trioxide (SO3) in the production of sulfuric acid. However, the catalyst used in the contact process is susceptible to poisoning, which refers to the deactivation or reduction in its catalytic activity. One of the substances that can poison the catalyst is arsenic oxide (As2O3). Arsenic oxide can interact with the catalyst's active sites, blocking or inhibiting its ability to facilitate the desired chemical reaction.

Q110. The unit of rate constant is same as that of rate of reaction in:

• A. First order reaction
• B. Zero order reaction✓
• C. Second order reaction
• D. Third order reaction

Explanation: Rate law general form:Rate = k[A]n n = order of reactionk = rate constantUnit of k depends on the order:k = Rate[A]n

Q111. The formula CH3(CH2)14COO- Na represents a member of the class of compounds called :

• A. Steroids
• B. Carbohydrates
• C. Vitamins
• D. Soap✓

Explanation: The formula CH3(CH2)14COO-Na represents a soap compound. Soaps are salts of fatty acids and are commonly used for cleaning purposes. The formula indicates the presence of a long hydrocarbon chain (CH3(CH2)14) attached to a carboxyl group (COO-) that forms a salt with sodium (Na+). Soaps are known for their ability to dissolve in water and form micelles, which help in the removal of dirt and oil from surfaces.

Q112. Four moles of electrons (4 x 6.02 x 1023 electrons) would electroplate how many grams of silver from a silver nitrate solution ?

• A. 216
• B. 324
• C. 432✓
• D. 540

Explanation: Explanation for this question will be added soon.

Q113. Electronic configuration of Cu is :

• A. 3d10 4s1✓
• B. 3d11 4s0
• C. 3d10 4s2
• D. 3d10 4s0

Explanation: The electronic configuration of copper (Cu) is obtained by filling the orbitals in order of increasing energy. The atomic number of copper is 29, which means it has 29 electrons. The electron configuration of copper can be determined by following the Aufbau principle, which states that electrons fill the lowest energy levels first. The electron configuration for copper can be written as: 1s2 2s2 2p6 3s2 3p6 4s2 3d9 However, when it comes to copper, there is an exception. Copper prefers to have a fully-filled 3d subshell rather than a half-filled 3d subshell due to increased stability. Therefore, one electron from the 4s orbital is promoted to the 3d orbital, resulting in the electron configuration: 1s2 2s2 2p6 3s2 3p6 4s1 3d10

Q114. The silky finish of mercerized cotton is obtained by treating cotton with a solution of:

• A. NaOH✓
• B. NaHCO3
• C. Na2CO3
• D. Na2CO3. 2H2O

Explanation: Mercerization is an industrial process involving sodium hydroxide for cotton yarns or fabrics to increase the luster and dyeability.It is a chemical treatment for cellulosic material such as cotton fibres for yarns. The yarn is dipped in a 20% sodium hydroxide bath, followed by an acid bath.In mercerization cotton fabric is treated with caustic soda which swells up the cotton fibers in cotton fabric adding below properties.• Improved luster• Increased ability to absorb dye• Improved reactions with a variety of chemicals• Improved stability of form• Improved strength/elongation• Improved smoothness• Improved hand

Q115. The amount of heat required to raise the temperature of 1 Calorie of substance through 1 K is called:

• A. Heat capacity
• B. 1 Joule
• C. Specific beat✓
• D. One calorie

Explanation: The Correct MCQ should be “The amount of heat required to raise the temperature of 1g of substance through 1K is called” Specific heat is the amount of energy needed to raise the temperature of 1g of substance by 1K.

Q116. Which one f the following has the lowest pH?

• A. 1 M HF
• B. 1 M HCL
• C. 1 m CH3COOH✓
• D. 1 M NaOH

Explanation: As we know that lower the pH, stronger the acid and greater the no of hydrogen ions in a solution. The acidity of an acid is measured by the ability to remove hydrogen ion.

Q117. The etectrical conductivity of NaCl crystal is:

• A. More than NaBr crystal
• B. Less than NaBr crystal
• C. Equal to NaBr crystal
• D. NaCl crystal doesn't conduct electric current✓

Explanation: In solid form, NaCl does not conduct electricity because its ions are locked in place within the crystal lattice and cannot move freely. For a substance to conduct electricity, it must have free-moving charged particles, which solid NaCl lacks. However, when NaCl is molten or dissolved in water, the ions are free to move, allowing it to conduct electricity. NaBr behaves similarly, with neither conducting in solid form, but both conducting when molten or in solution. Therefore, options A, B, and C are incorrect because they assume electrical conduction in solid form.

Q118. What type(s) of bonds is/are present in NH4 Cl?

• A. Ionic
• B. Covalent
• C. Co-ordinate covalent
• D. All of them✓

Explanation: An ionic bond forms between the NH4 + and Cl - ions in an NH 4 Cl molecule, as well as three covalent bonds between one atom N and three atoms of H and one coordinate covalent bond between N and other atom of H (NH4 +).

Q119. In which case the genotypic and.phenolypic ratio·will be 1:2:1?

• A. Option A: Complete-dominance
• B. Option B: Incomplete dominance✓
• C. Option C: Co-dominance
• D. Option D: None

Explanation: The correct answer is Option B: Incomplete dominance. In cases of incomplete dominance, the heterozygous offspring exhibit a phenotype that is a blend of the two homozygous phenotypes, leading to a genotypic ratio of 1:2:1 and a corresponding phenotypic ratio of 1:2:1. This is distinct from complete dominance, where one allele masks the other (Option A), resulting in a 3:1 phenotypic ratio. Co-dominance (Option C) allows both alleles to be fully expressed, but does not yield a 1:2:1 ratio. Lastly, Option D is incorrect because incomplete dominance does indeed fulfill the condition specified in the question.

Q120. You are electrolyzing potassium salt of a dicarboxylic acid in aqueous solution. Which product do you expect to be formed?

• A. Option A✓
• B. Option B
• C. Option C
• D. None

Explanation: Kolbe's electrolysis method is a general method of preparation of substituted hydrocarbons from the substituted carboxylic acids by the use of the electric discharge method where carbon dioxide gas is released. It is one of the most widely used methods for the preparation of alkanes and substituted hydrocarbons. Kolbe's electrolysis method is a general method of preparation of substituted hydrocarbons from the substituted carboxylic acids by the use of the electric discharge method where carbon dioxide gas is released. It is one of the most widely used methods for the preparation of alkanes and substituted hydrocarbons.

Q121. Formaldehyde give and addition product with methyl magnesium iodide. Which one aqueous hydrolysis gives:

• A. CH3OH
• B. C2H5OH✓
• C. (CH3)2CHOH
• D. ....

Explanation: When a Grignard reagent reacts with aldehydes and ketones, it results in production of addition products which on hydrolysis gives primary, secondary and tertiary alcohol. The reaction is carried in presence of ether followed by H3O+. 1. When Grignard reagent reacts with methanal, it results in production of primary alcohol. 2. When Grignard reagent reacts with ethanal, it results in production of secondary alcohol. 3. When Grignard reagent reacts with ketone, it results in production of tertiary alcohol.

Q122. The oxidation number of iron in (Fe( CN)6) -4 is:

• A. +3
• B. +2✓
• C. +4
• D. +6

Explanation: OPTION B is correct as there six ligands in the compound which is a cyano group having a charge of -1. Since there are six ligands so the total negative charge is -6. The Fe atom in the compound is the transition element which accepts electron from the ligand. The Fe atom in the compound has +2 charge. So, the total charge on the compound will be given as -6+2

Q123. The longest bond is of:

• A. H-I
• B. H-O
• C. H-S✓
• D. H-Cl

Explanation: The correct option is C: H-S. The bond length between hydrogen and sulfur is longer due to the relatively lower electronegativity of sulfur compared to oxygen and chlorine, and its larger atomic radius compared to iodine. While iodine is larger, the specific context here considers typical bond lengths with hydrogen, where H-S is longest among the options. H-O and H-Cl are shorter because of higher electronegativity differences, leading to stronger, shorter bonds. H-I might seem long due to iodine's size, but in comparison with H-S in terms of typical bond strength and length, H-S is longer.

Q124. The ideal gas equation is PV = nRT the symbol n in SI unit represent:

• A. The number of molecules in the gas✓
• B. Avogadro's number
• C. The number of kilo-moles
• D. The number of molecules per unit volume

Explanation: The ideal gas law can be written in terms of the number of molecules of gas: PV = nRT, where P is pressure, V is volume, T is temperature, n is number of molecules, and R is the general gas constant. PV = nRT, The pressure of a gas times its volume equals the number of moles of the gas times a constant (R) times the temperature of the gas. The ideal gas law is the final and most useful expression of the gas laws because it ties the amount of a gas (moles) to its pressure, volume and temperature.

Q125. London dispersion forces (forces between the particles) are present in:

• A. Gases only
• B. Liquids only
• C. Solids only
• D. All of the above✓

Explanation: The London dispersion force is the weakest intermolecular force. The London dispersion force is a temporary attractive force that results when the electrons in two adjacent atoms occupy positions that make the atoms form temporary dipoles. This force is sometimes called an induced dipole-induced dipole attraction. London Dispersion Forces occurs when there is a momentary region of electron density in an atom or molecule. This momentary region is negative, giving the atom or molecule polarity. As an atom or molecule gets larger, they get more electrons, so the probability of there being a region of electron density increases. Gases have electrons, so they have London Dispersion Forces. However, their LDFs tend to be weaker as gaseous atoms and molecules tend to be smaller than liquid and solid atoms and molecules. The halogens provide an example for this concept. Fluorine and chlorine molecules exist as gases at room temperature, but iodine and bromine molecules exist as a liquid and solid respectively because they are larger molecules.

Q126. The fixing solution used in developing a negative in photography contains:

• A. Hydroquinone
• B. Sodium thiosulphate✓
• C. Pyfogallal
• D. AgBr

Explanation: Sodium thiosulfate (sodium hyposulfite), Na2S2O3, is used by photographers to fix developed negatives and prints; it acts by dissolving the part of the silver salts coated onto film which remain unchanged by exposure to light. Fixation is commonly achieved by treating the film or paper with a solution of thiosulfate salt. Popular salts are sodium thiosulfate—commonly called hypo—and ammonium thiosulfate—commonly used in modern rapid fixer formulae.

Q127. Dry CO2 is passed through grignard reagent in the presence of either as a solvent. The intermediate is decomposed with diluted HCI giving a compound 'X' identity 'X'.

• A. Primary alcohol
• B. Secondary alcohol
• C. Acetone
• D. Carboxylic acid✓

Explanation: When a Grignard reagent reacts with carbon dioxide, the reaction leads to the formation of a carboxylate salt as an intermediate. Upon acidification, typically with a dilute mineral acid like HCl, this intermediate is converted into a carboxylic acid. Therefore, the compound 'X' is a carboxylic acid.The other options are incorrect because: Primary alcohols are formed by the reaction of Grignard reagents with formaldehyde, secondary alcohols are formed with aldehydes other than formaldehyde, and acetone is a ketone that requires specific starting materials and conditions unrelated to the reaction with carbon dioxide.

Q128. To what volume in .... must 50.0ml of 3.50M H2SO4 be diluted in order to make 2 M H2SO4?

• A. 25
• B. 60.1
• C. 87.5✓
• D. 93.2

Explanation: The correct option is c 87.5 mL M1V1=M2V2 Where, M1⇒ Molarity of the initial solution = 3.5 M V1⇒ Volume of the initial solution = 50 mL M2⇒ Molarity of the resultant solution i.e. after dilution = 2 M V2⇒ Volume of the resultant solution 3.5×50=2×V2 V2=3.5×502=87.5 mL Therefore, the initial solution must be diluted to 87.5 mL

Q129. For reaction 3O2(e) ⇋ 2O3(e) : Kc = 10-56 at 25 °C one can predict

• A. More O3 is formed
• B. More reactants are consumed
• C. The forward reaction progresses to a large extent
• D. The backward reaction goes to near completion✓

Explanation: Explanation is given as image.

Q130. The magnitude of i.(j×k) is equal to?

• A. 0
• B. 1✓
• C. -1
• D. 2

Explanation: The given expression i.(j×k) is an example of a scalar triple product, which represents the volume of the parallelepiped formed by the vectors i, j, and k. Here, i, j, and k are the standard unit vectors along the x, y, and z axes, respectively. According to the right-hand rule, j×k = i. Therefore, the scalar triple product i.(j×k) simplifies to i.i, which equals 1 since i is a unit vector and the angle between identical vectors is 0 degrees, leading to cos(0) = 1. Thus, the magnitude of the scalar triple product is 1.The incorrect options can be ruled out based on the properties of orthogonal unit vectors:Option A: 0 is incorrect because the vectors are not coplanar.Option C: -1 would only be correct in a left-handed system, which is not applicable here.Option D: 2 is incorrect because the magnitude cannot exceed 1 for unit vectors.

Q131. Which one of the following isotopes of natural Uranium undergo reaction with slow neutron:

• A. 92U235✓
• B. 92U236
• C. 92U238
• D. 92U239

Explanation: 92U235 is the only naturally occurring isotope of uranium that is fissile (able to fission with slow neutrons).

Q132. Two waves of the same frequency and amplitude traveling in opposite direction along the same position are:

• A. Electromagnetic waves
• B. Microwaves
• C. Stationary waves✓
• D. Sound waves

Explanation: When two waves of the same frequency and amplitude moving with the same speed in the opposite direction along the same path, these types of waves are known as Stationary waves.

Q133. In simple A.C capacitive circuit:

• A. The voltage leads current by 900
• B. The voltage leads current by 1800
• C. The current leads voltage by 900✓
• D. The current and voltage are in phase

Explanation: In A.C capacitive circuits, the current leads the voltage by 90° because first, the current flows through the two plates of the capacitor, where the charge is stored, after that the charge accumulates at the plates of the capacitor and causes an establishment of a voltage difference.

Q134. The phenomenon of mutual induction is practically used in:

• A. Transformer✓
• B. Generator
• C. Galvanometer
• D. Avometer

Explanation: A transformer is the most common application of mutual induction that uses this phenomenon to change the values of alternating voltages and currents

Q135. The color coding of a carbon resistor is such that the first band is green and the second yellow. The third band is red and the fourth is silver. The value of resistance is

• A. 4500 ohm with 10% tolerance
• B. 5400 ohm with 10% tolerance✓
• C. 54000 ohm with 1% tolerance
• D. 4500 ohm with 10% tolerance

Explanation: The color coding on a carbon resistor is used to indicate the resistance value and tolerance. The first two bands (Green and Yellow) represent the first two significant digits of the resistance value: Green is 5 and Yellow is 4. The third band (Red) is the multiplier, indicating the number of zeros to add. Red corresponds to a multiplier of 100, so the resistance is 54 x 100 = 5400 ohms. The fourth band (Silver) indicates a tolerance of ±10%. Therefore, the correct answer is 5400 ohms with a tolerance of 10%.Other options are incorrect because they either misinterpret the color codes or the tolerance value indicated by the Silver band.

Q136. Uncertainty principle can be expressed as:

• A. ΔpΔx = h
• B. ΔEΔI=h
• C. Both (a) and (b)✓
• D. None

Explanation: The Heisenberg uncertainty principle explains that momentum and position of a particle cannot be simultaneously at the same time with 100% accuracy. Similarly it is also impossible to measure the energy of a particle and the time measurement with 100% accuracy. ΔpΔx = h Is the expression for uncertainty in momentum and position of a particle. ΔEΔI=h Is the expression for uncertainty in energy and time measurement of a particle according to the Heisenberg uncertainty rule.

Q137. The frequency of fundamental mode of a string stretched by a tension T and gaming mass m and length l is given by:

• A. f = 1⁄2 √T/ml
• B. f = 1/2l√lT/m = 1/2l √lT/m✓
• C. f = 1/2l√T/m
• D. f = 1/2√T/m

Explanation: Frequency is directly proportional to tension and inversely with mass . Formula from SHM.

Q138. The first law of thermodynamics can be expressed mathematically as:

• A. Δθ = Δu + Δw✓
• B. Δθ = Δu
• C. Δθ = Δw
• D. None

Explanation: First law of thermodynamics states “ energy can neither be created nor destroyed, it can only be altered/changed into different forms”. Δθ= Δu + Δw is one of the mathematical expression for first law of thermodynamics which explains that heat supplied to the system(Δθ) is equal to change in internal energy of the system(Δu) plus work done by the system on the surrounding(Δw).

Q139. What will be the effect on the speed of transverse waves on a string if the tension in the string remains constant but the diameter of the string doubles?

• A. Remains constant
• B. Becomes half✓
• C. Becomes double
• D. Becomes four times

Explanation: The speed of transverse waves on a string is given by the formula v = √(T/μ), where T is the tension and μ is the linear density (mass per unit length) of the string. When the tension remains constant and the diameter of the string doubles, the cross-sectional area (and consequently the mass of the string per unit length) increases by a factor of four, since area is proportional to the square of the diameter. This results in the linear density increasing by four times.Since v = 1/√μ, a fourfold increase in the linear density results in the speed of the wave being halved. Therefore, the correct answer is that the speed becomes half. The other options are incorrect because they do not account for the change in linear density appropriately.

Q140. A particle is moving in a circle of radius r with constant angular speed w . its acceleration directed towards the center of circle is:

• A. w/r
• B. w2/r
• C. w2r✓
• D. Wr2

Explanation: To find the centripetal acceleration of a particle moving in a circle, use the formula ac = w2r, where w is the angular speed and r is the radius of the circle. The correct option is w2r, as it correctly applies this formula.Option A (w/r) and Option B (w2/r) incorrectly apply dimensional analysis and do not represent acceleration. Option D (Wr2) incorrectly squares the radius, which is not part of the centripetal acceleration formula.

Q141. A string passes over a smooth pulloy and 3kg mass at one and a 5kg mass at the other and the acceleration of the masses is:

• A. 2.5 ms-2✓
• B. 0.25 ms-2
• C. 9.25 ms-2
• D. 2.8 ms-1

Explanation: Explanation is given as image.

Q142. Rest man energy of an electron is:

• A. 0.511 MeV✓
• B. 1 MeV
• C. 8.0 x 10-14 J
• D. None of the above

Explanation: The rest mass energy of a particle is calculated by the formula E = mc2, where m is the rest mass and c is the speed of light. For an electron, this works out to be approximately 0.511 MeV. Option A is correct because it provides this value in MeV, the unit typically used in particle physics. Option B is incorrect because it overestimates the energy. Option C provides the equivalent energy in joules, which is a correct value but not in the unit asked. Option D is incorrect because the correct answer is indeed present in the options.

Q143. To an observer stationary on a plateform a compared to a stationary clock and a moving clock clicks:

• A. slower✓
• B. faster
• C. same rate as stationary clock
• D. clicks negative time

Explanation: The correct answer is that the moving clock ticks slower as observed from a stationary platform. This phenomenon is explained by the theory of relativity, specifically time dilation, which states that a clock moving relative to an observer will measure time more slowly than a clock at rest with respect to that observer. Option B is incorrect because relativity does not allow for a moving clock to tick faster. Option C is incorrect because it contradicts the experimental and theoretical background of time dilation. Option D is incorrect because time cannot be negative, as time is always a positive measure moving forward.

Q144. In a transverse wave, the distance between a crest and a trough is equal to

• A. λ/2✓
• B. λ
• C. λ/4
• D. 2λ

Explanation: Distance between two consecutive crests = πDistance between consecutive crests and trough = λ/2

Q145. The wavelength of a wave traveling with.speed v·and having frequency f is:

• A. λ = v/f✓
• B. λ = vf
• C. λ = f/v
• D. None of above

Explanation: speed = frequency x wavelength Rearrange the formula and you get: wavelength = speed / frequency

Q146. The weight of a pilot diving down with an acceleration of 9.8ms -2 will become:

• A. Double
• B. Half
• C. Zero✓
• D. Negative

Explanation: When an object is in free fall, such as a pilot diving down with an acceleration equal to gravity (9.8 m/s-2), it experiences weightlessness. This occurs because the only force acting on the object is gravity, and there is no normal force counteracting it. Thus, the weight, which is the normal force exerted by a surface, is effectively zero. The other options are incorrect as they suggest changes to gravity or forces that do not apply in the context of free fall.

Q147. Energy of a photon having frequency 10 Hz will be:

• A. 6.63 x 10-19 J✓
• B. 6.63ev
• C. 6.63 x 10-21 J
• D. 6.63 x 10-15 ev

Explanation: Explanation is given as image.

Q148. Which one of the following is the correct presentation for Ksp?

• A. Option A
• B. Option B✓
• C. Option C
• D. Option D

Explanation: The solubility product constant, Ksp , is the equilibrium constant for a solid substance dissolving in an aqueous solution. It represents the level at which a solute dissolves in solution. The more soluble a substance is, the higher the Ksp value it has.

Q149. The unit of pressure is:

• A. Nm-2
• B. One Pascal
• C. One atmosphere
• D. All✓

Explanation: All of these options are correct

Q150. Ohm's law is valid only for currents following in:

• A. Metallic conductor✓
• B. Transistors
• C. Diodes
• D. Electric arcs

Explanation: Ohm's law states that the current through a conductor between two points is directly proportional to the voltage across the two points, assuming the temperature remains constant. This linear relationship (I = V/R) is valid primarily for metallic conductors. In contrast, transistors and diodes are semiconductor devices and exhibit nonlinear current-voltage characteristics, which means they do not follow Ohm’s law. Electric arcs involve ionized gases (plasma), which also do not adhere to linear Ohmic behavior.

Q151. The maximum height H attained by a projectile projected with initial velocity v = (v.o) is given by:

• A. Option A
• B. Option B✓
• C. Option C
• D. Option D

Explanation: Explanation is given as image

Q152. The present SI unit of time is defined as:

• A. 1/24 x 1/60 x 1/60 of a mean solar day
• B. The second as defined by the electronic digital watch
• C. Duration of 9,192,631,770 vibrations of a cesium-133 atom✓
• D. Minute

Explanation: The SI unit of time is the second, symbolized as 's'. The modern definition is based on the cesium-133 atom's vibrations: specifically, 9,192,631,770 vibrations. This provides a highly precise standard. Option A refers to an outdated definition based on the Earth's rotation, which is variable. Option B is incorrect because digital watches use the standard definition rather than define it. Option D is incorrect because a minute is a derivative unit, not the base SI unit.

Q153. A wire loop is moved parallel to a uniform magnetic field. The induced emf in the loop will:

• A. Be maximum
• B. Be zero✓
• C. Depend on the size of the coil
• D. None of above

Explanation: Since the coil is moving parallel to a uniform magnetic field, the magnetic flux associated with the coil will remain zero during the whole time. And as the magnetic flux associated with the coil is not changing during the motion, there will be no emf induced in the coil. Hence induced emf in the coil will be zero.

Q154. A man carries a 1kg body 10m horizontally on a level ground. The work done by man is :

• A. 10 J
• B. 1 J
• C. 0 J✓
• D. 5 J

Explanation: To calculate work done, the formula is Work = Force × Displacement × cos(θ), where θ is the angle between the force and displacement vectors. In this scenario, the force due to gravity acts vertically downwards, and the displacement is horizontal. Since these two directions are perpendicular, θ = 90 degrees, and cos(90°) = 0. Thus, the work done is 0 J as there is no component of the force in the direction of displacement. The other options are incorrect because they assume a non-existent horizontal force component.

Q155. The value of G at the moon as compared with its value at the earth is :

• A. Smaller
• B. Same✓
• C. Greater
• D. Zero

Explanation: The gravitational constant G is a fundamental constant of nature that expresses the strength of gravitational attraction between two masses. It is a universal constant, meaning it remains the same throughout the universe. Thus, the value of G is the same on the Moon as it is on Earth, or anywhere else.Options A, C, and D are incorrect because they suggest G can vary based on location, which contradicts the definition and understanding of G as a universal constant.

Q156. An object is placed between convex lens and its focus, the image formed is :

• A. Real inverted , in front of the lens
• B. Virtual, erect, in front of the lens✓
• C. Real erect behind the lens
• D. Real inverted behind the lens

Explanation: When an object is placed between a convex lens and its focus, the image formed is virtual, erect, and located on the same side as the object (in front of the lens). This is because a convex lens is a converging lens, meaning it brings parallel rays of light together.

Q157. A p-type crystal is formed when Ge or SI crystal is doped with an impurity which is:

• A. Nonviolent
• B. Divalent
• C. Trivalent✓
• D. Pentavalent

Explanation: A p-type crystal is formed when a semiconductor crystal, such as Germanium (Ge) or Silicon (Si), is doped with an impurity that has one less valence electron than the atoms of the crystal. This impurity is known as a "trivalent" impurity. When a trivalent impurity is added to the crystal lattice, it replaces some of the original atoms, creating "holes" or vacant spaces in the crystal's valence band. These holes act as positive charge carriers. The trivalent impurity donates one of its valence electrons to the crystal, creating a positively charged "dopant" ion and leaving behind a vacant spot in the crystal structure. This addition of trivalent impurities effectively increases the concentration of positively charged holes in the crystal lattice, creating a surplus of positive charge carriers and hence leading to the formation of a p-type semiconductor.

Q158. A setup transformer is that which :

• A. Increase of power
• B. Increase of current
• C. Increase of voltage✓
• D. Increase of energy

Explanation: A step-up transformer is a type of transformer that increases the voltage of an alternating current (AC) while decreasing the current. It consists of two coils of wire, known as the primary coil and the secondary coil, which are wrapped around a common iron core. The primary coil is connected to the input voltage source, and the secondary coil is connected to the load or the device that requires a higher voltage. When an AC current flows through the primary coil, it creates a changing magnetic field in the iron core. This changing magnetic field induces a voltage in the secondary coil according to Faraday's law of electromagnetic induction. The voltage ratio between the primary and secondary coils is determined by the ratio of the number of turns in each coil. In a step-up transformer, the number of turns in the secondary coil is greater than the number of turns in the primary coil. This arrangement allows the transformer to increase the voltage while decreasing the current.

Q159. Two coherent monochromatic sets of waves will interfere constructively in the region of superposition only if the path difference between them is :

• A. Half wavelength
• B. Integral number of wavelength✓
• C. Quarter wavelength
• D. Odd integral number of half wavelength

Explanation: For two coherent monochromatic sets of waves to interfere constructively in the region of superposition, the path difference between them must be an integral number of wavelengths. This condition ensures that the crests of one wave align with the crests of the other wave, resulting in constructive interference. When the path difference is an integral number of wavelengths, the waves will have corresponding points in phase, meaning the crests and troughs of the waves will align. This alignment leads to the constructive interference of the waves, resulting in a larger combined amplitude at the region of superposition.

Q160. Cadmium rods are used in a nuclear reactor for :

• A. Slowing down fast neutrons
• B. Speeding up slow neutrons
• C. Absorbing fast neutrons✓
• D. Regulating the power evel of the reactor

Explanation: Cadmium rods are used in a nuclear reactor for absorbing fast neutrons. Neutrons in a nuclear reactor can have different energies, and their behavior and interaction with materials vary accordingly. Fast neutrons are highly energetic and can cause unwanted reactions or increase the rate of fission in the reactor. To control and regulate the rate of fission reactions, control rods made of materials such as cadmium are inserted into the reactor core. Cadmium has a high neutron absorption cross-section, meaning it has a high probability of absorbing neutrons when they come into contact with it. By absorbing fast neutrons, the cadmium rods effectively reduce the number of available fast neutrons and help control the rate of fission reactions in the reactor. This process helps maintain a stable and controlled level of nuclear reactions, ensuring the safe and efficient operation of the reactor.

Q161. A solenoid has length ℓ and Number of turns. It carries a current I and the magnetic yield produced inside the solenoid will be :

• A. B = µ°NI ℓ✓
• B. B = µ ℓ / °Nℓ
• C. B = Nℓ / °ℓ
• D. B = µ ℓ ℓ / °N

Explanation: According to Ampere's law, the magnetic field (B) produced inside a solenoid is directly proportional to the product of the permeability of free space (µ₀), the current (I) flowing through the solenoid, and the number of turns per unit length (N/ℓ). Mathematically, it is represented as: B = µ₀NI/ℓ

Q162. Pair production can take place only if the energy E of the photon is:

• A. E = 0.52 Mev
• B. E < 1.02 Mev
• C. E < 0.52 Mev
• D. E > 1.02 Mev✓

Explanation: Pair production is a process in which a photon interacts with a nucleus or an atomic electron and produces an electron-positron pair. According to the principles of conservation of energy and momentum, pair production can only occur if the energy of the photon is greater than or equal to the rest mass energy of the particle pair being produced. In the case of electron-positron pair production, the rest mass energy is approximately 0.51 MeV for each particle, so the total minimum energy required is twice that, which is 1.02 MeV.

Q163. Two capacitors of capacitance 2µF each are connected in series to a power supply of 6 volt. The voltage across each capacitor is :

• A. 6 volt✓
• B. 1 volt
• C. 3 volt
• D. 2 volt

Explanation: When capacitors are connected in series, the total capacitance (C_total) is given by the reciprocal of the sum of the reciprocals of the individual capacitances (C1, C2, C3, ...): 1/C_total = 1/C1 + 1/C2 + 1/C3 + ... In this case, we have two capacitors of 2µF each connected in series. Plugging in the values, we get: 1/C_total = 1/2µF + 1/2µF Simplifying the expression: 1/C_total = 2/2µF 1/C_total = 1/µF C_total = µF So the total capacitance is 1µF. Now, the voltage across each capacitor in a series circuit is the same. Therefore, the voltage across each capacitor in this case is 6 volts.

Q164. Transistor in a circuit basically acts as:

• A. Vallage amplifier
• B. Oxillator
• C. Current amplifier✓
• D. Rectifier

Explanation: A Transistor is a device which consists of three regions of doped semiconductors in which the current flowing is modulated by the voltage or current applied to one or more electrodes. These includes: Emitter- Heavily doped and function is to emit the charges. Collector- Moderately Doped and function to collect the charges Base- Lightly Doped and functions to reduce the transit time of charge. In PN Transistors there are two types: NPN – in which electrons are majority charge carriers (these are most widely used as the mobility of electrons is three times more than the holes and operation is faster within these transistors) PNP- in which holes are majority charge carriers A Transistor works as an amplifier by increasing the strength of the signal. A signal can be used to refer to any particular current, voltage, or power in a circuit. BUT… within these transistors there are three types of configurations: Common Emitter Configuration, Common Base Configurations and Common Collector Configurations Among these configuration Common emitter configurations is the most widely used (Book Statement KPK/FTB Pg no 246). Common emitter configurations are used when large current gains are needed, therefore for this MCQ, Current Amplifier is the most preferable option.

Q165. The orbital veIocity of a satellite orbiting around the earth at distance ....

• A. Option A✓
• B. Option B
• C. Option C
• D. Option D

Explanation: Minimum velocity required to put satellite in a circular orbit is called orbital velocity. Minimum height of satellite revolving orbiting around the earth is 400km and 24 such satellites GPS system. The centripetal force required to put the satellite in a circular path is provided by gravitational force. • If velocity of satellite is less than the critical velocity (v<27000km/h) it will fall towards earth. • If velocity of satellite is equal to critical velocity (v=27000km/h) then it will move in circular path • If velocity of satellite is greater than critical velocity but less than escape velocity it will move in an elliptical velocity. • If velocity is equal or greater than escape velocity it will escape from earth’s gravity.

Q166. A meter rod is moving with speed of light with respect to a stationary observer. The length of the rod will appear to the observer as approaching:

• A. Infinite
• B. Zero m✓
• C. 2 meter
• D. None of above.

Explanation: Formula for length contraction is L=L0√1−v2/c2, where: • L = new length (m) • L0 = original length (m) • v = speed of object (ms−1) • c = speed of light (~3.00⋅108ms−1) So, L=√1−c2/c2 =√1−1 =√0 L=0 meter

Q167. The final image formed by a two lens compound microscope is:

• A. Real, erect
• B. Real inverted
• C. Virtual inverted✓
• D. Virtual erect

Explanation: The objective lens produces a real, inverted image and the eyepiece acts as a simple magnifier and does not re-invert and produces a virtual image. So overall the image is inverted and virtual.

Q168. A nucleus emits gamma (γ) photon what happens to its atomic number and actual mass:

• A. Atomic number and actual mass remain unchanged✓
• B. atomic number and actual mass both decrease
• C. atomic number and actual mass both increase
• D. atomic number remains the same but the actual mass decrease

Explanation: Radioactivity is the phenomena in which an unstable nuclei emits alpha particle, beta particle or gamma ray in order to achieve stability. Thus the nuclei being unstable and having high energy is transmuted to stable nuclei. The stable nuclei is called daughter nuclei.

Q169. For a H-atom which one of the following statements is correct?

• A. The radius of the orbits are integral multiple of the Bohr-radius ...... 0.053mm
• B. The angular momentum is n times h/2π✓
• C. The energy in the nth-orbit is n times the ground state energy.
• D. Missing

Explanation: This option is correct as the angular momentum is n times h/2pi which is given by the formula : L=nh/2pi or mvr=nh/2pi which is stated in one of the Bohr’s postulate. It can have only quantized values which are situated with the orbits rather having values in between the orbits.

Q170. If an amount of work △W is done by an agent in time interval △t, the power of that agency Will be:

• A. △W /△t✓
• B. △t / W△
• C. △t / △W
• D. △W + △t

Explanation: Thus power is defined as the rate of transfer of energy. In other words, we also define power. The amount of work done by a body in a one second is called power. If W is work done by a body in time t then, power is given by: P=W/t

Q171. The number.of significant figures in the measurement of 5.05 X 10-3 ms-1 is:

• A. 2
• B. 3✓
• C. 4
• D. 8

Explanation: Please read the following explanation:

Q172. The molecular of oxygen has two unpaired electrons. It is therefore:

• A. diamagnetic
• B. paramagnetic✓
• C. ferromagnetic
• D. electromagnetic

Explanation: Those substances which have at least only one unpaired electron are called diamagnetic substances. They are weakly repelled in direction of magnetic field.

Q173. The dimension of torque are :

• A. (MLT)
• B. (M2 42 L)
• C. (ML2 T-2)✓
• D. (ML2 T2)

Explanation: The SI unit for torque is the Newton-metre or kgm2sec-2. Torque has the dimension of force times distance, symbolically T−2L2M. Although those fundamental dimensions are the same as that for energy or work, official SI literature suggests using the unit newton metre (N⋅m) and never the joule.

Q174. In Compton effect, the photon scattered at an angle of 90°. The Compton's shift of wave length wiil be:

• A. Option A✓
• B. Option B
• C. Option C
• D. Option D

Explanation: Please read the following page:

Q175. A person haviog a mass of 60kg exerts a horizontal force of 150N in horizontal floor with constant velocity, Net force is:

• A. 90N
• B. 60N
• C. 150N✓
• D. 100N

Explanation: The Correct Option is C as the person is moving with a net force of 150N in horizontal direction. Net force is defined as the force after all the forces acting on a body have been added. For example if a book is lying on a table, it is in rest because all the forces acting on the book after being added is zero so the net force on book is zero. But in the above mcq the forces acting on the person after being added are not zero and has horizontal direction. Thus Net force acting on the person is 150N in horizontal direction.

Q176. A 50Ω resistance wire is stretched such that its length is doubled and its cross section area becomes half. The new resistance is:

• A. 100Ω
• B. 200Ω✓
• C. 50Ω
• D. 150Ω

Explanation: The resistance R of a wire is given by the formula: R = ρL/A, where ρ is the resistivity, L is the length, and A is the cross-sectional area. When the wire is stretched such that its length doubles and its cross-sectional area is halved, the new length L' is 2L and the new area A' is A/2. The new resistance R' is given by:R' = ρ(2L)/(A/2) = 4ρL/A = 4RTherefore, the new resistance is four times the original resistance, which means R' = 4 * 50Ω = 200Ω.Options A (100Ω) and D (150Ω) are incorrect as they do not correctly account for the quadrupling of resistance. Option C (50Ω) is incorrect because it suggests no change in resistance, which is not possible under these conditions.

Q177. Why is it easiar to turn a steering wheel with both hands than with single.hand?

• A. The applied force is doubled.
• B. Two equal forces act concurrently on the wheel.
• C. A couple acts on the wheel.✓
• D. Two equal and opposite forces act concurrently on the wheel.

Explanation: Explanation is given as image.

Q178. Identify the following Clause:I want to see what had happened.

• A. Noun clause✓
• B. Adjective clause
• C. Adverb clause
• D. Independent clause

Explanation: Noun Clause (Correct): A noun clause functions like a noun in a sentence. In this case, "what had happened" acts as the direct object of the verb "want to see." It fills the position where a noun would typically go to complete the meaning of the sentence ("I want to see something").

Q179. Identify the following Clause:I expect that I shall get a prize.

• A. Noun clause✓
• B. Adjective clause
• C. Adverb clause
• D. Independent clause

Explanation: Noun Clause (Correct): A noun clause functions like a noun in a sentence. In this case, "that I shall get a prize" acts as the object of the verb "expect." It fills the position where a noun would typically go to complete the meaning of the sentence ("I expect something").

Q180. On a hot day or in hot climates white clothes are worn because they are good:

• A. Reflectors✓
• B. Absorbers
• C. Radiators
• D. Emitters

Explanation: White clothes are worn on hot days or in hot climates because they are good at reflecting sunlight. Light-colored and especially white fabrics reflect a significant portion of the sun's rays, helping to keep the body cooler. This is because lighter colors absorb less heat compared to darker colors. The reflection of sunlight reduces the absorption of thermal energy, contributing to a cooler feeling when wearing white clothes in hot weather.

Q181. Which theory explains that energy exchange takes place in discrete “bundles” or “quanta”?

• A. Special theory of relativity
• B. Quantum theory✓
• C. Corpuscular theory
• D. Bohr’s theory

Explanation: The theory that explains that energy exchange takes place in discrete "bundles" or "quanta" is quantum theory. This concept was first introduced by Max Planck in 1900 when he proposed that energy is quantized and exists in discrete packets. Subsequently, quantum theory was further developed by scientists like Albert Einstein, Niels Bohr, Werner Heisenberg, and Erwin Schrödinger, leading to the establishment of quantum mechanics. In quantum mechanics, the behavior of particles, including energy exchanges, is described in terms of discrete units or quanta.

Q182. Mathematically quantum theory is stated as:

• A. Option A
• B. Option B✓
• C. Option C
• D. Option D

Explanation: E = hfThis equation is a key element in understanding the quantization of energy in quantum theory. It shows that energy is quantized in discrete packets or quanta, with the energy of each quantum directly proportional to the frequency of the associated electromagnetic wave.

Q183. A single quantum of electromagnetic radiation is:

• A. Photon✓
• B. Proton
• C. Meson
• D. Positron

Explanation: A single quantum of electromagnetic radiation is called a "photon." Photons are elementary particles that represent a discrete amount of energy associated with electromagnetic waves. The energy of a photon is quantized and is directly proportional to the frequency of the associated electromagnetic wave. Photons exhibit both wave-like and particle-like properties, and they play a crucial role in the quantum theory of electromagnetic radiation.

Q184. Light consists of particle wave called:

• A. Proton
• B. Electron
• C. Neutron
• D. Photon✓

Explanation: The light particle conceived by Einstein is called a photon. Photons exhibit both wave-like and particle-like properties, and they play a crucial role in the quantum theory of electromagnetic radiation.

Q185. Rest mass of photon is:

• A. Infinite
• B. Zero✓
• C. Equal to proton
• D. None of the above

Explanation: Photons are massless particles. The rest mass of a photon is zero. Unlike particles with mass, such as electrons or protons, photons do not have rest mass. Because light always travels with some speed and is never at rest. So it has zero rest mass. Irrespective of the intensity, all the photons which have the same frequency, possess the same energy.

Q186. Due to the deficiency of _ hormone, synthesis of glycogen gets depressed, glucose level increases in blood and leads to a condition called Diabetes mellitus.

• A. Oxytocin
• B. Parathormone
• C. Glucagon
• D. Insulin✓
• E. Cortisol

Explanation: Diabetes mellitus is a metabolic disorder characterized by high levels of glucose in the blood due to the inability of the body to produce or respond to the hormone insulin. Insulin is produced by the beta cells of the pancreas and is responsible for glucose uptake from the blood into the cells, where it can be used as energy or stored as glycogen. When insulin is deficient, as in the case of diabetes, glycogen synthesis gets depressed, and glucose levels increase in the blood.

Q187. During active membrane potential, _ conducts the impulse in the form of nerve impulse.

• A. Axon
• B. Soma
• C. Neuron✓
• D. Cytoplasm
• E. Ribosome

Explanation: The neuron is the basic unit of the nervous system and consists of three main parts: the cell body (soma), dendrites, and axon. During active membrane potential, the neuron conducts an electrical impulse in the form of a nerve impulse or action potential. The impulse travels along the axon, a long, thin extension of the neuron, and is transmitted to other neurons, muscles, or glands.

Q188. The most important function of _ hormone is cell division in apical meristem of young plants.

• A. Gibberellins
• B. Ethylene
• C. Cytokinins
• D. Auxins✓
• E. Abscisic acids

Explanation: Auxins are plant hormones that play a crucial role in regulating plant growth and development. One of their main functions is to promote cell division in the apical meristem of young plants, which is the area of the plant responsible for growth in length. Auxins also help control plant growth orientation, and promote the formation of roots and fruits.

Q189. Norepinephrine:

• A. Is released by sympathetic fibers✓
• B. Is released by parasympathetic fibers
• C. Decrease the heart rate
• D. Decrease blood pressure
• E. Released by sympathetic fibers and decreases blood pressure

Explanation: Norepinephrine, also known as noradrenaline, is a neurotransmitter and hormone released by sympathetic fibers of the autonomic nervous system. Its effects on the body include increasing heart rate, constricting blood vessels, and raising blood pressure.

Q190. Neurons CANNOT undergo division, because they do not have.

• A. Centrosome✓
• B. Nucleus
• C. Mitochondria
• D. Golgi apparatus

Explanation: Option A: Neurons cannot undergo division because they do not have centrosomes. Centrosomes are organelles that help to organize microtubules, which are essential for cell division. Without centrosomes, neurons cannot properly divide and therefore cannot repair themselves or replace damaged cells. Option B: The nucleus contains the cell's DNA, which is essential for cell division. Option C: Mitochondria are responsible for generating energy for the cell. Option D: Golgi apparatus is responsible for processing and packaging proteins. All of these organelles are essential for the normal function of neurons, but they are not necessary for cell division.

Q191. Hypothalamus initiates the release of hormones, by their releasing factors, while _ is directly produced by it.

• A. TSH
• B. Oxytocin✓
• C. ACTH
• D. FSH
• E. GH

Explanation: Option A: TSH (thyroid-stimulating hormone) is released by the anterior pituitary gland in response to a releasing factor called thyrotropin-releasing hormone (TRH) from the hypothalamus. Option B: Oxytocin is released directly by the hypothalamus into the bloodstream. It is involved in childbirth, breastfeeding, and social bonding. Option C: ACTH (adrenocorticotropic hormone) is released by the anterior pituitary gland in response to a releasing factor called corticotropin-releasing hormone (CRH) from the hypothalamus. ACTH stimulates the release of cortisol from the adrenal glands. Option D: FSH (follicle-stimulating hormone) and LH (luteinizing hormone) are released by the anterior pituitary gland in response to releasing factors called follicle-stimulating hormone-releasing hormone (FSHRH) and luteinizing hormone-releasing hormone (LHRH) from the hypothalamus. FSH and LH are involved in the regulation of reproduction. Option E: GH (growth hormone) is released by the anterior pituitary gland in response to a releasing factor called growth hormone-releasing hormone (GHRH) from the hypothalamus. GHRH stimulates the release of GH, which is involved in growth and development.

Q192. Functions of the brainstem include all of the following EXCEPT:

• A. Integration of righting reflexes
• B. Autonomic control for respiration
• C. Equilibrium and posture regulation
• D. Initiation of voluntary movements✓
• E. Fixation of the eyes

Explanation: Option A: Integration of righting reflexes: The brainstem plays a crucial role in integrating and coordinating reflexes that help maintain an upright posture and balance in response to changes in body position. Option B: Autonomic control for respiration: The brainstem contains respiratory centers that regulate and control the automatic process of breathing, including the rhythm and depth of respiration. Option C: Equilibrium and posture regulation: The brainstem, along with other brain structures, contributes to the maintenance of balance, coordination, and posture. It receives sensory information from the inner ear and coordinates motor responses to help keep the body stable and oriented. Option D: Initiation of voluntary movements: The initiation of voluntary movements primarily involves higher brain regions, such as the motor cortex. While the brainstem is involved in coordinating and refining movements, it does not directly initiate voluntary movements. Option E: Fixation of the eyes: The brainstem includes structures responsible for controlling eye movements and coordinating the fixation of gaze. It ensures that the eyes can move together smoothly and accurately to focus on specific targets.

Q193. What part of the brain integrates sensory information such as pain and temperature?

• A. Forebrain✓
• B. Midbrain
• C. Hindbrain
• D. Spinal cord

Explanation: Option A: Forebrain is the part of the brain that is responsible for higher-level functions, such as thinking, planning, and decision-making. It includes the thalamus, hypothalamus, amygdala, hippocampus, and cerebral cortex. The part of the brain that integrates sensory information, such as pain and temperature, is the thalamus. The thalamus is a relay center for sensory information, meaning that it receives information from sensory receptors throughout the body and then sends it to the appropriate parts of the brain for processing. The thalamus is located in the forebrain, specifically in the diencephalon. Option B: The Midbrain is the part of the brain that is responsible for connecting the forebrain and hindbrain. It includes the tectum, tegmentum, and substantia nigra. Option C: The Hindbrain is the part of the brain that is responsible for basic functions, such as breathing, heart rate, and balance. It includes the medulla oblongata, pons, and cerebellum. Option D: The Spinal cord is a long, thin bundle of nerves that runs from the brainstem to the lower back. It is responsible for transmitting sensory information from the body to the brain and for sending motor commands from the brain to the body.

Q194. Glands and muscles are activated by:

• A. Sensory neurons
• B. Associative neurons
• C. Relay neurons
• D. Motor neurons✓

Explanation: Option A: Sensory neurons transmit information from the environment to the central nervous system (CNS). Option B: Associative neurons integrate information from sensory neurons and send signals to motor neurons. Option C: Relay neurons transmit signals from one part of the CNS to another. Option D: Motor neurons activate glands and muscles. Motor neurons are the final pathway in the nervous system that controls the contraction of muscles and the secretion of glands. They receive signals from associative neurons and send signals to the muscles and glands. The signals from motor neurons are called motor impulses. Motor impulses cause muscles to contract and glands to secrete.

Q195. The system involved in preparing our body in condition of stress and emergency:

• A. Nervous system only
• B. Endocrine system only
• C. Both nervous & endocrine system✓
• D. Both endocrine & exocrine

Explanation: The answer is both nervous and endocrine system. The nervous system is responsible for detecting danger and sending signals to the body to prepare for a fight-or-flight response. The endocrine system then releases hormones that help the body to respond to the stress. These hormones, such as adrenaline and cortisol, increase heart rate, blood pressure, and blood sugar levels. They also prepare the body for physical activity by increasing muscle strength and endurance.

Q196. Which of the following helps in maintaining balance?

• A. Hypothalamus
• B. Medulla Oblongata
• C. Cerebellum✓
• D. Pons

Explanation: The cerebellum is a part of the hindbrain that helps in maintaining the posture and balance of the body. The hypothalamus has several endocrine functions involving thermoregulation. Pons regulate the sleep-wake cycle. Medulla Oblongata controls involuntary movements such as breathing, heart rate, etc.

Q197. Sensation of pleasure, punishment, or sexual arousal are stimulated by the parts of the brain:

• A. Hippocampus
• B. Hypothalamus
• C. Amygdala✓
• D. Thalamus

Explanation: The amygdala controls the sensation of pleasure, punishment, or sexual arousal. The hippocampus has a major role in learning and memory. The hypothalamus is considered to be a link structure between the nervous and the endocrine system; its main function is to maintain the homeostasis of the body. The thalamus has several functions, such as relaying of sensory signals, including motor signals, to the cerebral cortex and the regulation of consciousness, sleep, and alertness.

Q198. Goiter is one of the abnormalities due to a deficiency of a hormone:

• A. Adrenaline
• B. Thyroxine✓
• C. Oxytocin
• D. Parathormone

Explanation: The most common cause of goitres worldwide is a lack of iodine in the diet. In the United States, where the use of iodized salt is common, a goitre is more often due to the over- or under-production of thyroid hormones or to nodules in the gland itself.