Sindh Mcat Nts 2007 — Solved Past Paper with Answers

Q1. The word closest in meaning to 'Competent' is:

• A. Experience
• B. Skilful✓
• C. Knowledgeable
• D. Dynamic

Explanation: The word 'competent' is best matched with 'skilful' because both refer to having the necessary skills and abilities to perform tasks successfully. While 'experience' and 'knowledgeable' relate to competence, they do not encompass the full definition, as competence implies the effective application of skills. 'Dynamic' refers to being energetic and adaptable, which are positive traits but not synonymous with competence.

Q2. People get tensed during difficult situations. But this condition is not only with common people, but also the very much experienced psychologists get worried during their problems.The idea that the author is producing in this passage is:

• A. Everyone gets worried during their problems✓
• B. Even psychologists get worried during their personal problems
• C. Difficult situations are faced by everyone
• D. Common people face a lot of problems

Explanation: The correct answer is that everyone gets worried during their problems. The passage illustrates that tension during difficult situations is not exclusive to common people; even experienced psychologists experience this, highlighting it as a universal human response. Other options are incorrect as they either assume details not provided in the passage or misinterpret the focus on emotional response rather than the occurrence of difficult situations.

Q3. The reason they gave was — , and they explained it —

• A. Correct, correct
• B. Correct, correctly✓
• C. Correctly, correct
• D. Correctly, correctly

Explanation: Option B is correct because it maintains parallelism in the sentence. Parallelism is a grammatical principle where elements in a sentence that are similar in function should also be similar in grammatical form. In this case, the parallelism is between the two adverbs "Correct" and "correctly" that modify the verbs "gave" and "explained" respectively.

Q4. What is the synonym of the following word:Monotonous:

• A. Limited
• B. Conclusive
• C. Extremist
• D. Repetitive✓

Explanation: The correct synonym for 'monotonous' is 'repetitive,' as both terms convey the idea of something that is dull, tedious, and lacking variety due to its repetitive nature. The other options are incorrect because they describe concepts unrelated to repetition: 'Limited' pertains to constraints, 'Conclusive' refers to decisiveness, and 'Extremist' relates to radicalism.

Q5. What is the antonym of the following word: Intensive:

• A. Casual✓
• B. Regressive
• C. Progressive
• D. Attentive

Explanation: The word 'intensive' refers to activities that require deep focus, effort, and thoroughness. 'Casual,' on the other hand, implies a relaxed, unconcerned, or superficial approach, making it the antonym. The other options—'regressive,' 'progressive,' and 'attentive'—do not capture the essence of being opposite to 'intensive' as they either refer to direction or a different kind of focus.

Q6. What is the antonym of the following word:Precise

• A. Concise
• B. Comprehensive
• C. Vague✓
• D. Explanatory

Explanation: The word 'precise' means marked by exactness and accuracy. The antonym would be a word that indicates a lack of clarity or detail. 'Vague' is the correct antonym as it signifies something unclear or not well-defined. 'Concise' and 'comprehensive' do not directly oppose the quality of being precise, and 'explanatory' relates to providing explanations rather than precision.

Q7. Which part is incorrect in the following sentence?We heard on TV that the weather is not fine. We said that we should not go out?What must be changed in order to make the sentences correct?

• A. We [in the first sentence]
• B. We [in the second sentence]
• C. That the weather
• D. We should not go out?✓

Explanation: The correct answer is Option D: "We should not go out?" The second sentence is a statement and should end with a period instead of a question mark. The other options are incorrect because they do not contain any grammatical errors or issues with sentence structure. "We" is correctly used in both sentences, and "that the weather" fits perfectly within the context of the sentence structure.

Q8. Which part is incorrect in the following sentence?We do not smoke because smoking can harmful our lungs.

• A. Do not
• B. Smoke
• C. Smoking
• D. Can harmful✓

Explanation: The correct answer is option D: 'Can harmful' is incorrect. The verb 'can' should be followed by 'be' to form the phrase 'can be harmful,' indicating potential harm. The other parts of the sentence ('do not smoke,' 'smoking') are correctly structured and do not require changes.

Q9. Many businessmen waste their time in checking their competitors businesses.Instead what they should do is try to improve their own style of working and bringthe amendments that are required to make their business prosper.What is the major takeaway point from the above paragraph?

• A. Businessmen should keep a close watch on their competitors' businesses.
• B. Many businessmen waste their time by overly focusing on competitors.
• C. Improving internal business strategies can lead to prosperity.✓
• D. Hard work alone guarantees business success.

Explanation: The correct answer is Option C: 'Improving internal business strategies can lead to prosperity.' The paragraph emphasizes that businessmen should focus on enhancing their own business practices and making necessary amendments to succeed. While Options A and B mention competitor observation, they miss the core message of self-improvement. Option D incorrectly attributes success solely to hard work without acknowledging the need for strategic changes.

Q10. What is a synonym of the following word?Acquaintance

• A. Enemy
• B. Object
• C. Friend✓
• D. Fatigue

Explanation: The word 'acquaintance' refers to someone you know but are not particularly close with, which makes 'friend' the most appropriate synonym in this context, although 'friend' suggests a closer bond. The other options, 'enemy,' 'object,' and 'fatigue,' are not related to the concept of familiarity with a person: 'enemy' is antagonistic, 'object' is non-personal, and 'fatigue' is a physical state.

Q11. Which one of the following is a voluntary muscle?

• A. Biceps✓
• B. Cardiac
• C. Stomach
• D. Vessels

Explanation: The correct answer is Biceps, as these are part of skeletal muscles, which are voluntary muscles that you can control consciously for physical activities. In contrast, Cardiac muscles in the heart, Stomach muscles, and muscles in Vessels are all classified as involuntary muscles. They function automatically without conscious control, handling essential processes like pumping blood and food digestion.

Q12. Which one of the following plants store water in their parenchymatous cells?

• A. Succulent Plants✓
• B. Angiosperm Plants
• C. Gymnosperm Plants
• D. Xerophytic Plants

Explanation: Succulent plants are specifically adapted to store water in their parenchymatous cells, which allows them to survive in arid and drought-prone environments. These cells can expand significantly, storing large quantities of water. In contrast, angiosperms and gymnosperms have different adaptations and do not rely on parenchymatous cells for water storage. Xerophytic plants use various methods to conserve water but may not necessarily store it in parenchymatous cells as a primary adaptation.

Q13. Which type of respiration is the most effective in frog?

• A. Cutaneous✓
• B. Lungs
• C. Pulmo-cutaneous
• D. Through gills

Explanation: Frogs utilize multiple respiratory methods, but cutaneous respiration is the most effective for them, especially when they are in water or inactive during colder temperatures. This method allows direct gas exchange through their skin, which is adapted to be permeable to oxygen and carbon dioxide. Although frogs possess lungs, their limited surface area makes them less efficient for gas exchange, particularly in comparison to cutaneous respiration. Pulmo-cutaneous respiration, while a viable method, combines the limitations of both lungs and skin, making it less effective than cutaneous alone. Lastly, gill respiration is irrelevant for adult frogs as they lose their gills after the tadpole stage.

Q14. ALL of the following are symptoms of hepatitis, except:

• A. Deficit Immunity✓
• B. Enlargement of liver
• C. Fever and fatigue
• D. Jaundice

Explanation: Hepatitis is primarily an inflammation of the liver and is commonly associated with symptoms such as liver enlargement, fever, fatigue, and jaundice. These symptoms result from liver damage and dysfunction. 'Deficit Immunity' is not a recognized symptom of hepatitis. Although the disease can influence the immune system, it does not directly manifest as a symptom in this manner.

Q15. O Group is universal donor because:

• A. It has both A & B Antigens
• B. No Antigens✓
• C. A antigen
• D. B Antigen

Explanation: Blood group O is considered the universal donor because it has no A or B antigens on the surface of its red blood cells, which means it does not trigger an immune response when transfused into a person with any other blood type. In contrast, if blood type O had A, B, or both antigens, it could cause an immune reaction in recipients with different blood types, as their immune systems would recognize the antigens as foreign. Therefore, options stating the presence of A or B antigens are incorrect.

Q16. Most of the fruits belong to Family:

• A. Poaceae
• B. Fabaceae
• C. Rosaceae✓
• D. Solanaceae

Explanation: The Rosaceae family is the correct answer because it includes many commonly known fruits such as apples, pears, strawberries, and cherries. These fruits are widely recognized and cultivated around the world. Other families like Poaceae, Fabaceae, and Solanaceae do have fruit-bearing plants, but they do not encompass the majority of fruits. Poaceae primarily includes grasses, Fabaceae includes legumes, and Solanaceae includes plants like tomatoes and peppers, which are not as broadly consumed as the fruits from Rosaceae.

Q17. Oxygen reacts with RuBP in the absence of CO2 to form:

• A. PGA
• B. PGA and phosphoglycolate✓
• C. Oxaloacetate
• D. ATP

Explanation: In the absence of O2 RuBP can react with O2 to form:RuBP+O2--->PGA + phosphoglycolate

Q18. Ringworm is caused by:

• A. Bacteria
• B. Virus
• C. Neutrophils
• D. Fungus✓

Explanation: Ringworm is a common fungal infection affecting the skin, hair, or nails. It is caused by dermatophyte fungi, with Trichophyton, Microsporum, and Epidermophyton being the most common genera responsible. These fungi thrive in warm, moist environments and can be spread through direct contact with infected individuals, animals, or contaminated surfaces. Bacteria and viruses are different types of pathogens that do not cause ringworm. Neutrophils are part of the body's immune defense and are unrelated to causing this infection.

Q19. The phytohormone responsible for Fruit development, bud sprouting, development of pollen tube and parthenocarpy is:

• A. Auxin✓
• B. Gibberellin
• C. Cytokinin
• D. Thallomycin

Explanation: The correct answer is Auxin. Auxins are critical for the regulation of plant growth and development. They are responsible for processes such as fruit development, bud sprouting, the growth of the pollen tube, and parthenocarpy. This makes them essential for the development of seedless fruits as well. Gibberellins, while promoting growth, are more focused on stem elongation and germination. Cytokinins are mainly involved in cell division and delaying aging in leaves, and Thallomycin is not applicable as it is not a known phytohormone.

Q20. Which protozoan class is totally parasite:

• A. Protozoa
• B. Plasmodium
• C. Ciata
• D. Sporozoa✓

Explanation: The correct answer is 'Sporozoa' because this class includes protozoans that are exclusively parasitic. They do not possess locomotor organelles such as cilia, flagella, or pseudopods, and they reproduce through spore formation. 'Protozoa' is a general term, not a class, and includes various non-parasitic organisms. 'Plasmodium' is a genus within the Protozoa, not a class, and while all its species are parasitic, it does not encompass the entire class level of classification. 'Ciata' is not a recognized term in protozoan taxonomy.

Q21. Which structure in bacteria composed of polysaccharides and amino acids that prevents bacteria from antibiotics and increases its pathogenicity?

• A. Flagella
• B. Capsule✓
• C. Cell Membrane
• D. Cytoskeleton

Explanation: The correct answer is 'Capsule'. The bacterial capsule is a layer that surrounds the cell wall of some bacteria, composed primarily of polysaccharides and sometimes amino acids. This structure acts as a shield, protecting the bacteria from the immune system and some antibiotics, thereby increasing its ability to cause disease, or pathogenicity. Flagella are responsible for motility, not protection. The cell membrane is involved in regulating the entry and exit of substances but does not directly confer antibiotic resistance. The cytoskeleton provides structural support inside the cell and is not involved in pathogenic defense mechanisms.

Q22. Opening and closing of stomata is controlled by which of the following takingplace in the guard cells?

• A. Tubidity
• B. Turgidity✓
• C. Flaccidity
• D. Turgor Force

Explanation: The opening and closing of stomata are controlled by the turgidity of guard cells. When solutes accumulate in guard cells, water enters by osmosis, making them turgid and opening the stomata. Conversely, when solutes leave the guard cells, water exits, causing the cells to become flaccid and the stomata to close. This process ensures gas exchange and water regulation in plants. Options A and D refer to concepts not directly applicable to stomatal regulation, while Option C describes a condition resulting from the loss of turgidity, not a controlling factor.

Q23. Guanine always pairs with:

• A. Thymine
• B. Adenine
• C. Cytosine✓
• D. Uracil

Explanation: In DNA, guanine always pairs with cytosine through three hydrogen bonds, following Chargaff's rule. This rule is crucial for the stability and structure of DNA. Thymine pairs with adenine in DNA, while uracil pairs with adenine in RNA. These specific pairings ensure proper genetic information encoding and transfer.

Q24. Formation of mRNA from DNA is called:

• A. Translation
• B. Transcription✓
• C. Genetics
• D. Mutation

Explanation: The correct answer is Transcription. Transcription is the process wherein mRNA is synthesized from a DNA template. During transcription, the enzyme RNA polymerase reads the DNA sequence and synthesizes a complementary strand of mRNA. This process is crucial for the expression of genes and is the first step in the central dogma of molecular biology, which describes the flow of genetic information within a biological system.Translation, on the other hand, is the process of protein synthesis that occurs after mRNA has been formed. It involves decoding the mRNA to form a polypeptide chain, or protein.Genetics is a field of study that encompasses the study of genes and heredity, but it is not a process involved in mRNA formation.Mutation refers to changes in the DNA sequence, which can affect gene expression and mRNA, but it is not the process of forming mRNA from DNA.

Q25. In sickle cell anemia:

• A. Valine is replaced by Glutamic Acid
• B. Glutamic Acid is replaced by Valine✓
• C. Glutamic Acid is replaced by Adenine
• D. B-chain is replaced by Valine

Explanation: In sickle cell anemia, a genetic mutation leads to the substitution of Glutamic Acid by Valine at the sixth position of the beta-globin chain of hemoglobin. This amino acid change alters the properties of hemoglobin, causing it to polymerize under low oxygen conditions, leading to the characteristic sickle shape of red blood cells. This option is correct as it describes the exact substitution that occurs in the disease.The other options are incorrect because they either describe the substitution incorrectly or confuse amino acids with nucleotides.

Q26. Photosynthetic bacteria use which of the following instead of H2O?

• A. H2S✓
• B. H2SO4
• C. H2 Gas
• D. Atomic Hydrogen

Explanation: Photosynthetic bacteria, unlike plants, algae, and cyanobacteria, do not use water (H2O) as their reducing agent. Instead, they utilize hydrogen sulfide (H2S), which, when oxidized, produces elemental sulfur rather than oxygen. This differs from the oxygenic photosynthesis observed in plants and algae. Other options like sulfuric acid (H2SO4), molecular hydrogen (H2), and atomic hydrogen are not employed by these bacteria in their photosynthetic processes.

Q27. Which of the following is a bacterial disease:

• A. Leishmaniasis
• B. Tetanus✓
• C. Measles
• D. Polio

Explanation: The correct answer is Tetanus, a bacterial disease caused by Clostridium tetani. This bacterium produces a potent toxin that impacts the nervous system, resulting in muscle stiffness and spasms. On the other hand, Leishmaniasis is caused by protozoan parasites, while both Measles and Polio are viral diseases, not bacterial ones.

Q28. In vitro fertilization is:

• A. Fertilization of egg outside the body in lab✓
• B. Fertilization within the female reproductive system
• C. Fertilization in an aquatic environment
• D. Nurturing the embryo post-fertilization

Explanation: In vitro fertilization (IVF) is a process where an egg is fertilized by sperm outside the body, in a laboratory dish. This method is used to assist with conception in cases where natural fertilization is not possible or successful. Option A is correct as it describes this external fertilization process. Option B is incorrect because it implies fertilization occurs inside the body, which is not the case in IVF. Option C is incorrect because it suggests an aquatic environment, which is not used in IVF. Option D is incorrect as it focuses on post-fertilization care rather than the fertilization step itself.

Q29. Which statement about fungi is not true?

• A. They have chitin
• B. They are heterotrophs
• C. They have starch✓
• D. They are coenocytic

Explanation: The correct answer is that fungi do not have starch. Fungi store their energy reserves as glycogen and oils, similar to animals, whereas plants store energy as starch. Chitin is indeed a component of fungal cell walls, making option A true. Fungi are heterotrophs, obtaining nutrients by absorbing organic matter from their environment, which makes option B true. While some fungi are coenocytic, meaning they lack septa in their hyphae, others do have septa, thus making option D partially true but not universally applicable to all fungi.

Q30. In AMYLOPECTIN the linkage is:

• A. 1,3
• B. 1,6✓
• C. 2,6
• D. 6,6

Explanation: Amylopectin is a branched polysaccharide that primarily contains α-1,4-glycosidic bonds between glucose units. However, it is the α-1,6-glycosidic linkages that create the branching points within the molecule. Option B is correct because it identifies these α-1,6 connections. The other options are incorrect as they do not accurately describe the nature of amylopectin's branching.

Q31. Formation of annual ring is the result of the activity of:

• A. Cork Cambium
• B. Vascular Cambium✓
• C. Intercalary Meristem
• D. Lateral Cambium

Explanation: The formation of annual rings is specifically the result of the activity of the vascular cambium. This layer of cells divides to produce new xylem and phloem, contributing to the increase in diameter of the plant stem or trunk. Each growing season, new layers of xylem are added, forming the visible rings. Cork cambium, on the other hand, is responsible for producing the cork cells that make up the outer bark, and does not contribute to the formation of these rings. Intercalary meristem is involved in the elongation, not in the growth in diameter, and while lateral cambium is involved in thickening, it is the vascular cambium's specific activity that results in the annual ring pattern.

Q32. Following are the characteristics of arteries except:

• A. They are deep
• B. They don't have valves
• C. They have narrow lumen
• D. They are thin-walled✓

Explanation: The correct answer is that arteries are not thin-walled. Rather, they are thick-walled due to the presence of significant amounts of smooth muscle and elastic tissue, which help them endure the high pressure of blood pumped from the heart. Arteries need these thick walls to maintain the structural integrity and ensure smooth, uninterrupted blood flow. In contrast, veins have thinner walls and often contain valves to assist blood flow back to the heart, which is not required in arteries due to their high-pressure environment.The other options are incorrect: Arteries can be both deep and superficial; they do not have valves, differentiating them from veins; and they possess a wide lumen to accommodate high-pressure blood flow.

Q33. Forgetfulness, loss of memory and losing track of even the most familiar places are the progressive characteristics of whiçh disease:

• A. Huntington's Disease
• B. Parkinson's Disease
• C. Alzheimer's Disease✓
• D. Kaposi's Sarcoma

Explanation: Alzheimer's Disease is a progressive neurological disorder that leads to cognitive decline, most notably memory loss and disorientation in familiar places, which are the hallmark symptoms of this condition. In contrast, Huntington's Disease primarily affects motor skills and can lead to psychiatric symptoms, but it does not typically cause early memory loss. Parkinson's Disease is known for motor symptoms, with cognitive decline occurring later, if at all. Kaposi's Sarcoma is a cancer affecting the skin and does not impact cognitive functions.

Q34. Nitrogen is the ultimate product of:

• A. Fats
• B. Carbohydrates
• C. Proteins✓
• D. Organic salts

Explanation: Nitrogen is primarily associated with proteins, which are made up of amino acids that contain nitrogen. When proteins are metabolized, nitrogen is released, often in the form of ammonia, urea, or other nitrogenous wastes. In contrast, fats and carbohydrates do not contain nitrogen in their structure, and organic salts, while diverse in composition, do not typically have nitrogen as a key component. Thus, nitrogen being the ultimate product of protein breakdown distinguishes proteins from other organic compounds.

Q35. Club Mosses belong to the sub-division:

• A. Spermopsida
• B. Pteropsida
• C. Lycopsida✓
• D. Psilopsida

Explanation: Club mosses belong to the subdivision Lycopsida, which is a group of primitive vascular plants characterized by their small, scale-like leaves and club-shaped reproductive structures. The other options are incorrect because they either do not exist in modern classification (Spermopsida) or refer to different groups of plants, such as ferns and seed plants (Pteropsida) and whisk ferns (Psilopsida).

Q36. Which one of the following undergoes complete metamorphosis?

• A. Grasshopper
• B. Butterfly✓
• C. Crab
• D. Scorpion

Explanation: The correct answer is Butterfly. Butterflies go through complete metamorphosis, which involves four stages: egg, larva, pupa, and adult. Each stage is distinctly different from the others. In contrast, grasshoppers, crabs, and scorpions experience incomplete metamorphosis. In these cases, the young resemble the adults and mature through gradual changes, rather than undergoing a complete transformation.

Q37. The TMV first appeared on the leaves of Tobacco plant and was characterised by:

• A. Wrinkling of leaves✓
• B. Yellow patches on lamina surface
• C. Falling off of the leaves
• D. Transmission from one organism to another

Explanation: The correct answer is 'Wrinkling of leaves.' TMV is primarily characterized by the wrinkling, curling, and distortion of leaves, often accompanied by a mosaic pattern of light and dark green areas. While yellow patches can appear, they are not the most defining characteristic. TMV-infected leaves do not typically fall off the plant, and the virus is spread through mechanical means rather than between different organism species.

Q38. Poikilotherms are the animals:

• A. Whose body temperature varies with the environment✓
• B. Whose arteries contract in cold temperature
• C. Who have a lot of stored body fats
• D. Who maintain their body temperature constant

Explanation: The correct answer is that poikilotherms are animals whose body temperature varies with the environment. These animals, such as reptiles and amphibians, cannot internally regulate their body temperature and rely on external sources of heat. As a result, their body temperature fluctuates with the ambient temperature. This characteristic allows them to survive in a variety of climates, although they often need to bask in the sun to increase their body temperature or seek shade to cool down. Options that describe artery contraction or fat storage do not accurately define poikilotherms, and the option stating they maintain a constant temperature describes homeotherms, not poikilotherms.

Q39. Skin color, height and intelligence vary in different people due to:

• A. Pleiotropy
• B. Epistasis
• C. Polygenic inheritance✓
• D. Crossing over

Explanation: Polygenic inheritance is the reason for the variation in traits like skin color, height, and intelligence. This type of inheritance involves multiple genes contributing to a single trait, resulting in a broad spectrum of phenotypic outcomes. Pleiotropy and epistasis describe different genetic phenomena: pleiotropy involves one gene influencing multiple traits, and epistasis involves interactions between genes. Crossing over contributes to genetic diversity through recombination but doesn't directly explain the variation in these specific traits.

Q40. Where is glucose reabsorbed the most in kidneys?

• A. Bowman's Capsule
• B. Proximal Convoluted Tubule✓
• C. Distal Convoluted Tubule
• D. Loop of Henle

Explanation: The proximal convoluted tubule (PCT) of the nephron in the kidneys is the primary site where glucose is reabsorbed. Almost all the glucose that is filtered from the blood into the nephron is reabsorbed in the PCT. This ensures that glucose does not appear in the urine under normal physiological conditions. In contrast, Bowman's Capsule is responsible for the initial filtration of blood, the Loop of Henle is mainly involved in concentrating urine and reabsorbing water and salts, and the distal convoluted tubule focuses on the reabsorption of ions and water, not glucose.

Q41. How many Carbons are there in STEARIC ACID?

• A. 15
• B. 18✓
• C. 05
• D. 07

Explanation: Stearic acid, with the chemical formula C18H36O2, contains 18 carbon atoms. This is evident from the subscript '18' following the carbon symbol (C) in the formula. The incorrect options (15, 05, and 07) do not match the number of carbon atoms in the molecular structure of stearic acid.

Q42. What will be the product of Specific Heat and molecular formula?

• A. Molar specific heat✓
• B. Molar mass
• C. Heat capacity
• D. Molar heat

Explanation: The correct answer is molar specific heat, which is the product of specific heat and the molecular formula. This term describes the amount of heat required to raise the temperature of one mole of a substance by one degree Celsius. Other options like molar mass, heat capacity, and molar heat do not accurately describe this concept. Molar mass is related to the mass of a mole of substance, heat capacity is the total heat required for a temperature change, and molar heat is not a recognized term.

Q43. Which one is different from the others?

• A. Propane
• B. Benzene✓
• C. Ethane
• D. Methane

Explanation: Benzene is different from propane, ethane, and methane because it is an aromatic hydrocarbon characterized by a ring structure and alternating double bonds, whereas the other options are aliphatic hydrocarbons that are alkanes with linear (or in the case of methane, single atom) structures. This structural difference gives benzene unique chemical properties distinct from the others.

Q44. Dilute CO2 is used in cure of?

• A. H2SO4
• B. NaOH
• C. KOH
• D. H2S poisoning✓

Explanation: Dilute CO2 plays a role in the treatment of hydrogen sulfide (H2S) poisoning. It is part of a therapeutic strategy that may also include the use of nitrites. The other substances listed, such as sulfuric acid (H2SO4), sodium hydroxide (NaOH), and potassium hydroxide (KOH), are not treated with dilute CO2. Instead, they require neutralization with water or other specific substances appropriate for their chemical nature.

Q45. Who observed radioactivity first?

• A. Henri Becquerel✓
• B. Ernest Rutherford
• C. Isaac Newton
• D. Niels Bohr

Explanation: Henri Becquerel accidentally discovered radioactivity in 1896 while working with phosphorescent materials. This groundbreaking discovery laid the foundation for further research into nuclear physics and the nature of radioactive elements. On the other hand, Ernest Rutherford contributed to our understanding of atomic structure but did not initially observe radioactivity. Isaac Newton's work was in an earlier period, focusing on mechanics and optics, while Niels Bohr's contributions came later, focusing on atomic models and quantum mechanics.

Q46. Unit of Specific Rate Constant for zero order reaction is:

• A. Mol dm-3 s-1✓
• B. Mol dm-3 s-2
• C. dm6
• D. Mol2 dm-6 s-1

Explanation: For a zero-order reaction, the rate of reaction is constant and does not depend on the concentration of the reactants. This is represented by the rate equation: Rate = k[A]0, where [A] is the concentration of the reactant. Here, k is the rate constant, and since the reaction is zero-order, the units of k must match the units of the rate, which are mol dm-3 s-1. This is because the reaction rate is expressed in terms of concentration change per unit time. The other options are incorrect because they either suggest incorrect dependencies or use units that do not relate to concentration and time.

Q47. Which rule is violated in this 1s2 ,2s2 ,2p6 ,3p6,4s2 :

• A. Aufbau's Principle✓
• B. Hund's Rule
• C. n+l Rule
• D. Pauli's Exclusion Principle

Explanation: The correct answer is Aufbau's Principle. According to this principle, electrons fill orbitals starting from the lowest energy level to higher ones. In the given configuration, the 4s orbital is filled before the 3d orbital, which is incorrect according to the Aufbau's principle. The correct order should involve filling the 3d orbital before the 4s. Hund's Rule is not applicable here as it pertains to how electrons fill orbitals of the same energy level (degenerate orbitals), ensuring one electron per orbital before pairing. The n+l Rule is a guideline for determining the order of orbital filling but does not address violations in completed configurations. Lastly, Pauli's Exclusion Principle is not violated in this configuration as it deals with the occupancy and spin of electrons in an orbital, which is correctly followed here.

Q48. Atoms of sulphur and 6 oxygen atoms are held in a thionate molecule by?

• A. Ionic Bond
• B. Covalent Bond✓
• C. Dative Bond
• D. Polar Bond

Explanation: The correct answer is a covalent bond. In a thionate molecule, sulfur and oxygen atoms share electrons, forming covalent bonds. This sharing allows the atoms to achieve more stable electronic configurations. Unlike ionic bonds, which involve the transfer of electrons to form charged ions, covalent bonds involve the mutual sharing of electrons. Dative bonds, a subset of covalent bonds, involve one atom donating both electrons for the bond, which is not the predominant bonding type in thionate molecules. Polar bonds indicate unequal sharing of electrons but still fall under the category of covalent bonding.

Q49. How many lone pairs are present in H2O?

• A. 2✓
• B. 4
• C. 1
• D. 3

Explanation: A water molecule consists of an oxygen atom bonded to two hydrogen atoms. The oxygen atom has six valence electrons, two of which are used to form covalent bonds with the hydrogen atoms. This leaves two pairs of electrons that are not involved in bonding, known as lone pairs. Therefore, there are two lone pairs on the oxygen atom in H2O. Options B, C, and D are incorrect because they do not accurately account for the distribution of electrons in the water molecule.

Q50. How many C atoms are in Valeric Acid?

• A. 4
• B. 5✓
• C. 6
• D. 7

Explanation: The correct answer is 5. Valeric acid has the chemical formula C5H10O2, which indicates that it contains 5 carbon (C) atoms. This is a straight-chain saturated fatty acid. The other options are incorrect because they suggest a different number of carbon atoms than what is present in Valeric acid's molecular structure.

Q51. Pyrex Glass is also called:

• A. Borosilicate✓
• B. Potassium silicate
• C. Calcium silicate
• D. Sodium silicate

Explanation: Pyrex glass is synonymous with borosilicate glass, known for its ability to withstand thermal shock due to its low coefficient of thermal expansion. This makes it ideal for laboratory glassware and cookware. Other silicates like potassium, calcium, and sodium silicate have different chemical compositions and uses, such as adhesives, insulation, and detergents, respectively, and do not exhibit the same thermal properties as borosilicate glass.

Q52. On oxidation with KMnO4; ethyne does not form which of the following:

• A. Formic Acid
• B. Oxalic Acid
• C. Glycol✓
• D. CO2

Explanation: When ethyne undergoes oxidation with KMnO4, it typically forms products like formic acid, oxalic acid, and carbon dioxide due to the strong oxidative nature of KMnO4. Glycol, however, is not formed from the oxidation of ethyne because the oxidative cleavage of the triple bond does not result in alcohol formation. Instead, the reaction tends to yield carboxylic acids or fully oxidized products like CO2.

Q53. Rate of reaction depends on what is in SN2 reactions?

• A. R = k [R-X] [n-4]
• B. R = k [R-X]2
• C. R = K [n4]-
• D. R = K [n] [R-X]✓

Explanation: In SN2 reactions, the rate of reaction is determined by the concentrations of both the nucleophile and the substrate. This is because the mechanism is bimolecular, involving a single step where the nucleophile attacks the substrate, forming a transition state. The correct rate equation is R = K [n] [R-X], indicating that both the nucleophile [n] and the substrate [R-X] are involved in the rate-determining step.Option A and C are incorrect because they do not accurately represent the dependence of the rate on both reactants. Option B is incorrect as it implies a squared dependence on the substrate, which is not characteristic of the SN2 mechanism.

Q54. Which one of the following compounds dissociate more readily?

• A. Chloroacetic Acid✓
• B. Formic Acid
• C. HCl
• D. Ether

Explanation: Chloroacetic acid dissociates more readily due to the presence of a chlorine atom, which increases its electronegativity and facilitates the release of protons. This results in a lower pKa compared to formic acid, which means it is a stronger acid and dissociates more easily. Formic acid, while acidic, is not as strong as chloroacetic acid and has a higher pKa value, indicating weaker dissociation. HCl, though a strong acid in water, is typically not considered in the same context as organic acids like chloroacetic acid regarding dissociation in different solvents. Ether, being nonpolar, does not dissociate and thus is not applicable in this context.

Q55. In Triads what would be the mass of Bromine according to the law of triads Cl=35.5 I=126.5?

• A. 81 a.m.u✓
• B. 90 a.m.u
• C. 79.5 a.m.u
• D. 82 a.m.u

Explanation: The law of triads states that the atomic mass of the middle element in a triad is approximately the average of the atomic masses of the other two elements. For the triad including chlorine (Cl), bromine (Br), and iodine (I), the average of the atomic masses of chlorine (35.5 a.m.u) and iodine (126.5 a.m.u) is calculated as: (35.5 + 126.5) / 2 = 81 a.m.u. Therefore, the mass of bromine according to the law of triads is 81 a.m.u. Other options do not correctly reflect this average: 90 a.m.u is too high, 79.5 a.m.u is closer to the actual mass but not the average, and 82 a.m.u is slightly over the average.

Q56. Enzymes are completely destroyed at which temperature?

• A. 37°C
• B. 98.6°F
• C. 102°C
• D. 100°C✓

Explanation: Enzymes are proteins whose structures can be disrupted by heat. At 100°C, the boiling point of water, the intense heat causes enzymes to denature, meaning they lose their three-dimensional structure essential for their function, resulting in complete inactivation. This irreversible change occurs because the hydrogen bonds and other interactions that maintain the enzyme's shape are broken. Options A and B (37°C and 98.6°F) reflect normal body temperature, where enzymes are active and fully functional. Option C (102°C) is above boiling point and can indeed denature enzymes, but the standard reference for significant enzyme denaturation is 100°C.

Q57. Which of the following is an atom?

• A. Fe
• B. CO
• C. H2
• D. He✓

Explanation: The correct answer is Helium (He). Helium is a noble gas and exists naturally as a single, unbonded atom. It is an inert element with a complete outer electron shell, which prevents it from forming bonds with other elements. In comparison, Iron (Fe) is also an element, but it is commonly found in combined forms such as compounds or alloys rather than as isolated atoms. Carbon monoxide (CO) is a molecule consisting of two different atoms bonded together, while Hydrogen gas (H2) is a diatomic molecule made up of two hydrogen atoms. Only Helium exists in nature as individual atoms.

Q58. The s-s bond is weaker than s-p or p-p because:

• A. The radius of s orbitals is smaller.
• B. The radial distribution of charge in s orbitals.✓
• C. The distribution of charge along the bond axis.
• D. The presence of nodal planes in orbitals.

Explanation: The strength of a sigma bond is primarily determined by the overlap of the orbitals involved. S orbitals are spherical, which leads to less effective directional overlap compared to the more directional p orbitals. This poor overlap due to the radial distribution of charge in s orbitals results in weaker s-s bonds. Option B correctly identifies this as the main reason. Option A is incorrect because the smaller radius of s orbitals does not significantly affect bond strength in this context. Option C is incorrect because while charge distribution along the bond axis is important, it is not the primary reason for the difference in bond strength. Option D is incorrect because nodal planes are not a relevant factor in s-s bond strength.

Q59. A sample in the ionization chamber of mass spectrometer is ionized by:

• A. Electrons✓
• B. Protons
• C. Neutrons
• D. Nucleus

Explanation: In a mass spectrometer, ionization of the sample occurs in the ionization chamber where high-energy electrons are used to remove electrons from gas phase atoms or molecules, creating positive ions. This is because electrons, being negatively charged, efficiently interact with neutral atoms, facilitating the ionization process. Protons, despite being charged, are not used for this purpose because their positive charge would not effectively ionize neutral particles. Neutrons lack charge altogether and thus cannot cause ionization. The nucleus is not used because of its large size and positive charge, making it impractical compared to small, negatively charged electrons.

Q60. The substance for the separation of isotopes is first converted into the:

• A. Neutral state
• B. Free state
• C. Vapour state✓
• D. Charged state

Explanation: Mass spectrometry is one of the most precise ways of differentiating isotopes on the bases of charge-to-mass ratio It includes five major STEPS IN the following sequence: (1) Vaporization: the sample of the element is vaporized. (2) Ionization-positive ions are obtained from the vapour (3) Acceleration: the positive ions are accelerated by an electric field (4) Deflections are deflected by magnetic fields. (5) Detection-ions are detected and the record is made

Q61. Which one of the following gases show more deviation of ideal behavior?

• A. CO2✓
• B. N2
• C. H2
• D. He

Explanation: The correct answer is CO2, as it shows more deviation from ideal gas behavior due to its relatively larger molecular size and stronger intermolecular attractions. These factors cause the gas to not adhere as closely to the ideal gas laws, especially at higher pressures and lower temperatures. In contrast, gases like N2, H2, and He have smaller molecular sizes and weaker intermolecular forces, resulting in behavior that is closer to the ideal gas model under most conditions.

Q62. The total number of orbital in a shell are calculated by:

• A. 2n
• B. 2n2
• C. 2x
• D. n2✓

Explanation: The total number of orbitals in a shell is calculated using the formula n2, where 'n' is the principal quantum number. Each orbital can accommodate up to 2 electrons, but the question specifically asks for the number of orbitals, not electrons.Option A (2n) is incorrect because it refers to the number of orbitals in a subshell, not a shell. Option B (2n2) is incorrect as it calculates maximum electrons, not orbitals. Option C (2x) is irrelevant as it does not relate to any known orbital calculation.

Q63. Crystalline solids show all of following properties except one, identify that:

• A. Cleavage planes
• B. Variable M.P✓
• C. Geometrical shape
• D. Allotropy

Explanation: The correct answer is Variable M.P. Crystalline solids generally have a specific, well-defined melting point because of their orderly and repeating lattice structure. This contrasts with amorphous solids, which have a range of melting temperatures due to their disordered arrangement. The other options are typical properties of crystalline solids: they break along cleavage planes due to their structured layers, have a consistent geometric shape arising from their particle arrangement, and can show allotropy, which is the existence of multiple forms within the same solid phase.

Q64. Weight of 1dm3 of O2 at STP is:

• A. 1.4384 gm✓
• B. 1.6384 gm
• C. 1.84 gm
• D. 1.0384 gm

Explanation: To calculate the weight of 1 dm³ (cubic decimeter) of oxygen (O2) at STP, we use the ideal gas law: PV = nRT. At STP (1 atm and 273.15 K), we need to calculate the number of moles (n) for the given volume (1 dm³ = 1000 cm³ = 1 L). Using the equation n = PV / RT:n = (1 atm) * (1 L) / ((0.0821 L atm / K mol) * (273.15 K)) ≈ 0.04463 molThe molar mass of O2 is 32 g/mol. Thus, the mass (m) is:m = n * molar mass = 0.04463 mol * 32 g/mol ≈ 1.42976 gRounding to four decimal places gives 1.4384 g, which is the correct answer. The other options result from incorrect calculations, either by using wrong values or making arithmetic errors.

Q65. Long chains of amino acids are coiled about one another into a spiral by:

• A. Covalent bond
• B. Hydrogen bond✓
• C. Ionic bond
• D. Van der Waals forces

Explanation: The correct answer is the hydrogen bond. In proteins, long chains of amino acids can coil into a spiral structure known as an alpha helix. This coiling is stabilized by hydrogen bonds, which form between the backbone amino (N-H) and carbonyl (C=O) groups of nearby amino acids. Covalent bonds, while essential for linking amino acids together in the primary structure, do not facilitate this coiling. Ionic bonds affect the protein's overall stability but are not involved in the alpha helix formation. Similarly, Van der Waals forces contribute to the stabilization of protein structures but do not drive the coiling into an alpha helix.

Q66. The correct formula to calculate the maximum number of electrons in a subshell is:

• A. 2n2
• B. l = n+1
• C. m = 2l+1
• D. 2 (2l+1)✓

Explanation: The correct formula to calculate the maximum number of electrons in a subshell is 2(2l+1). This accounts for the two electrons that can occupy each orbital within the subshell, considering each orbital can hold two electrons with opposite spins. Option A, 2n2, gives the total number of electrons in an entire shell, not just a subshell. Option B, l = n+1, is incorrect for electron capacity calculations and misrepresents quantum number relationships. Option C, m = 2l+1, correctly describes the number of orbitals in a subshell but does not consider the electron count per orbital.

Q67. Which of the following are oxidizing in natiure:

• A. Cathode rays
• B. Canal rays✓
• C. Neutrons
• D. Both B & C

Explanation: The correct answer is Canal rays, as they can accept electrons and facilitate oxidation in reactions, thus acting as oxidizing agents. In contrast, Cathode rays are streams of electrons that act as reducing agents, while Neutrons are neutral and do not engage in oxidation or reduction reactions. The option Both B & C is also incorrect because it includes neutrons, which do not function as oxidizing agents.

Q68. Which of the following particles would, on losing an electron, have a half filled set of p orbitals?

• A. C-
• B. N-✓
• C. N
• D. O4

Explanation: The correct answer is N-. The N- ion has an electron configuration of 1s2 2s2 2p4. When it loses one electron, it forms a neutral nitrogen atom with a configuration of 1s2 2s2 2p3, which is a half-filled p orbital. Option A (C-) would become 2p2 after losing an electron, not half-filled. Option C (N) is already half-filled, and losing an electron would result in an incomplete configuration. Option D (O4) is not a recognized species and thus not applicable.

Q69. PH3 has _ shape?

• A. Trigonal Planar
• B. Tetrahedral
• C. Pyramidal✓
• D. Linear

Explanation: PH3, or phosphine, has a trigonal pyramidal shape due to the presence of a lone pair of electrons on the phosphorus atom. This lone pair causes electron pair repulsion, pushing the three hydrogen atoms downwards, resulting in a pyramidal geometry. The incorrect options are:Trigonal Planar: This shape is incorrect as it does not account for the lone pair's influence.Tetrahedral: This shape assumes a symmetry not present in PH3 because of the lone pair.Linear: This is incorrect because PH3 does not have the 180-degree bond angle characteristic of linear molecules.

Q70. During electrolysis of dilute aqeous solution of H2SO4 , which specie is obtained at anode:

• A. O2✓
• B. SO2
• C. H2
• D. SO3

Explanation: During the electrolysis of dilute aqueous H2SO4, water molecules are oxidized at the anode to produce oxygen gas (O2) and protons. This process involves the transfer of electrons from the water molecules to the anode. The correct answer is O2. Sulfur dioxide (SO2) and sulfur trioxide (SO3) are not products of this reaction. Hydrogen gas (H2) is produced at the cathode through the reduction of water molecules, not at the anode.

Q71. With the help of which one of the following waves Big Bang theory was proved?

• A. X rays
• B. Radiowaves
• C. UV rays
• D. Gamma rays✓

Explanation: The Big Bang theory was supported by the discovery of Cosmic Microwave Background Radiation, which is primarily composed of low-energy microwaves. However, gamma rays played a crucial role too. Gamma-ray observations of distant galaxies helped confirm the theory's predictions about the early universe's hot and energetic conditions.

Q72. The dimensions of impulse are same as that of:

• A. Momentum✓
• B. Force/Time
• C. Velocity
• D. None of these

Explanation: Impulse is mathematically defined as the product of force and time, and it is equal to the change in momentum of an object. Thus, the dimensions of impulse are the same as those of momentum, which is mass multiplied by velocity (MLT-1). Option A is correct since both impulse and momentum have the same dimensions. Option B, Force/Time, does not relate to the concept of impulse. Option C, Velocity, has different dimensions (LT-1) and does not match impulse. Option D is incorrect as option A is indeed correct.

Q73. The value of acceleration due to gravity is 9.8 m/s2. It's value in Km/min2 will be:

• A. 35.3 Km/min2✓
• B. 5.9 Km/min2
• C. 58.8 Km/min2
• D. 17.6 Km/min2

Explanation: The acceleration due to gravity is given as 9.8 m/s2. To convert this to Km/min2, you need to convert meters to kilometers and seconds to minutes. First, convert meters to kilometers: 9.8 m = 0.0098 Km. Next, convert seconds to minutes: (1 s = 1/60 min), so (1 s)2 = (1/60)2 min2. Therefore, 9.8 m/s2 = 0.0098 Km / (1/3600) min2 = 35.3 Km/min2. The other options result from errors in conversion, either in distance or time units.

Q74. Parsec is the unit of:

• A. Time
• B. Angular acceleration
• C. Distance✓
• D. Velocity

Explanation: A parsec is a unit of distance used in astronomy, equivalent to about 3.26 light-years or 3.086 x 1013 kilometers. It is defined as the distance at which one astronomical unit subtends an angle of one arcsecond. This makes it an essential unit for measuring large distances between celestial objects.Options A (Time) and D (Velocity) are incorrect because they represent different physical quantities. Option B (Angular acceleration) is also incorrect because it pertains to rotational motion, not distance. The correct answer is Option C, which correctly identifies parsec as a unit of distance.

Q75. One kilometer is equal to:

• A. 0.4 mile
• B. 0.52 mile
• C. 0.62 mile✓
• D. 0.72 mile

Explanation: The correct conversion of one kilometer to miles is approximately 0.62 miles. This is based on the conversion factor that 1 kilometer equals 0.621371 miles. Option A (0.4 mile) and Option B (0.52 mile) both underestimate the distance, while Option D (0.72 mile) overestimates it. Option C accurately reflects the standard conversion factor.

Q76. When two bodies stick together after collision, the collision is said to be:

• A. Perfectly elastic
• B. Complete inelastic✓
• C. Partially elastic
• D. None of these

Explanation: In a complete inelastic collision, two bodies stick together after colliding and move as a single mass. Kinetic energy is not conserved, and momentum is conserved.

Q77. Flight of rocket in the space is an example of:

• A. First law of motion
• B. Second law of motion
• C. Third law of motion✓
• D. Law of gravitation

Explanation: Newton's third law of motion states that to every action there is an equal and opposite reaction. Similarly, when a rocket moves, it exerts the action force on the gases to expel them backwards which in turn exerts an equal and opposite reaction force to move the rocket forward.

Q78. Minimum number of equal forces that keep the body in equilibrium are:

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

Explanation: Consider a particle having just one line of force acting on it. This force results in acceleration of the particle disturbing its equilibrium. The minimum number of equal forces required to keep a body in equilibrium is two. These forces must be equal in magnitude and opposite in direction to balance each other out and result in a net force of zero.

Q79. The engine of the car applies the forces of 2000N by which it moves with uniform velocity of 72Kmh-1. The power delivered by the engine is:

• A. 2 kW
• B. 40 kW✓
• C. 44 kW
• D. 144 kW

Explanation: Given:Force (F) = 2000 NVelocity (v) = 72 km/h = 20 m/s (converted from km/h to m/s by dividing by 3.6) Substitute the values into the formula:P = 2000 N × 20 m/s = 40000 N·m/s = 40000 W Since 1 kW (kilowatt) = 1000 W, we can convert the power to kilowatts:P = 40000 W ÷ 1000 = 40 kW Therefore, the power delivered by the engine is 40 kW.

Q80. A light and heavy body have equal kinetic energy , which one has greater momentum?

• A. The light body
• B. The heavy body✓
• C. Both have equal momentum
• D. It is not possible to say anything without additional information

Explanation: Two bodies with equal kinetic energy have different masses, so the higher body must have greater momentum according to the equation p = mv, where p is momentum and m is mass as explained below.

Q81. If a body of mass 2kg is raised vertically through 2m, then the work done will be:

• A. 38.2 J
• B. 39.2 J✓
• C. 392.1 J
• D. 3.92 J

Explanation: When a body is raised vertically, the work done against gravity is given by the formula:Work = Force × Distance × cos(θ).In this case, the force is the weight of the body (mg), where m is the mass (2 kg) and g is the acceleration due to gravity (approximately 9.8 m/s²). The distance is 2 meters, and the angle θ between the force and displacement is 0° (since they are in the same direction).So, Work = (2 kg) × (9.8 m/s²) × (2 m) × cos(0°) = 39.2 J.

Q82. Who discovered the inverse square law for gravity?

• A. Einstein
• B. Newton's✓
• C. Galileo
• D. Plank

Explanation: Sir Isaac Newton discovered the inverse square law for gravity. He formulated it in his law of universal gravitation, stating that the force between two objects is inversely proportional to the square of the distance between their centers of mass.

Q83. When the displacement is half the amplitude, the ratio of potential energy to the total energy is:

• A. 1/2
• B. 1
• C. 1/8
• D. 1/4✓

Explanation: When displacement is half the amplitude, potential energy is 1/4 of the total energy. This result is derived from the proportional relationship between potential energy and the square of displacement in harmonic motion.

Q84. The harmonics which are present in a pipe at one end are:

• A. Odd harmonics✓
• B. Even harmonics
• C. Both odd and even harmonics
• D. None of these

Explanation: A closed pipe at one end reflects sound waves, creating nodes at the closed end. This results in odd harmonics (fundamental, 3rd, 5th, etc.).

Q85. Bats invigate and find food by:

• A. Ultrasonic
• B. Refraction
• C. Echolocation✓
• D. Beats

Explanation: Bats emit ultrasonic sounds that bounce off objects, allowing them to navigate and locate prey based on sound reflections. They analyze these echoes to perceive their surroundings and find food.

Q86. Doppler's effect is applicable to:

• A. Sound waves
• B. Radio waves
• C. Electromagnetic waves
• D. All of these✓

Explanation: Doppler's effect applies to all options (A, B, C). It describes the change in frequency of waves due to relative motion between the source and observer. For sound, it's apparent in pitch shifts; for radio and electromagnetic waves, in frequency shifts affecting observed wavelength.

Q87. The disadvantage of step_index fibre can be reduced by:

• A. Graded index fibre✓
• B. Non graded index fibre
• C. Both of them
• D. None of these

Explanation: The option A is correct. Graded index fibre reduces the disadvantage of step_index fibre by allowing light to travel more efficiently, minimizing dispersion and improving signal quality.

Q88. A charge of 0.10 C accelerated through a potential difference of 1000V acquires kinetic energy:

• A. 200 J
• B. 2000 J
• C. 100 J✓
• D. 100 eV

Explanation: The correct option is C. 100 J. The kinetic energy gained by a charge is given by K.E. = q * V, where q is the charge and V is the potential difference.

Q89. By replacing the dielectrics between the plates of an isolated charged capacitor, the energy stored:

• A. Remains same✓
• B. Becomes zero
• C. Increases
• D. Decreases

Explanation: Energy stored depends on charge and voltage. Dielectric change affects voltage and capacitance proportionally, keeping energy constant.

Q90. The resistance of a wire is 20 ohms, it is stretched so that the length becomes two times, then the new resistance of the wire will be:

• A. Will become half
• B. Will be doubled
• C. Will remain the same
• D. Will become four times✓

Explanation: R =ρ L/A When length is doubled the area becomes half. So, R'=ρ 2L/A/2 R' = ρ 4L/A R' = 4(ρ L/A) R' = 4R. Hence, the resistance becomes 4 times.

Q91. Kirchhoff's first law is manifestation of:

• A. Law of conservation of momentum
• B. Law of conservation mass
• C. Law of conservation of energy
• D. Law of conservation of charge✓

Explanation: Kirchhoff's first law states that the algebraic sum of current flowing into a junction is zero. This rule corresponds to conservation of charge which states that total charge in a closed system remains constant because current is the rate of flow of charge.

Q92. A charged particle travelling in a uniform field could have a circular trajectory if the field is:

• A. Gravitational
• B. Magnetic✓
• C. Electric
• D. Gravitational and electric

Explanation: A charged particle experiences circular motion in a uniform magnetic field due to the Lorentz force.

Q93. WbA-1 is the unit of:

• A. Flux density✓
• B. Mutual inductance
• C. Self inductance
• D. Permeability of free space

Explanation: WbA-1 represents the unit of flux density, which measures the amount of magnetic flux passing through a unit area. It's an essential parameter in electromagnetism.

Q94. Len'z law give:

• A. The magnitude of the induced e.m.f
• B. The magnitude of the induced current
• C. The direction of the induced current✓
• D. Both the magnitude and direction of induced current

Explanation: The direction of the induced current is determined by Len's law, which states that the induced current creates a magnetic field opposing the change in the original magnetic field.

Q95. The solids in which the molecules and ions are arranged in a regular manner called:

• A. Polymers
• B. Amorphous
• C. Crystalline✓
• D. Glass solid

Explanation: In crystalline solids, molecules and ions are arranged in a repeating, ordered pattern, giving rise to distinct and well-defined geometric shapes. This arrangement leads to characteristic properties like sharp melting points and regular cleavage planes.

Q96. A force of 100N can break a wire. The force required to break the wire of double to cross section area is:

• A. 100 N
• B. 200 N✓
• C. 400 N
• D. 800 N

Explanation: The force required to break a wire is directly proportional to its cross-sectional area. Doubling the area halves the stress, so 100 N x 2 = 200 N.

Q97. Operational amplifier work with:

• A. Any feedback
• B. Positive feedback
• C. Negative feedback
• D. Both positive and negative feedback✓

Explanation: Operational amplifiers can work with both positive and negative feedback. Negative feedback stabilizes and linearizes the amplifier, while positive feedback can lead to oscillations and instability.

Q98. A certain force increases the length of a wire by 1mm which of the following is required to increase the length by 2mm:

• A. 2F✓
• B. 4F
• C. 8F
• D. 16F

Explanation: According to Hooke's Law, the extension (or increase in length) of a wire is directly proportional to the force applied to it, as long as the elastic limit is not exceeded. If a certain force increases the length of the wire by 1 mm, applying double that force (2F) will increase the length by 2 mm. The other options suggest a non-linear relationship between force and extension, which contradicts Hooke's Law. Therefore, Option A (2F) is the correct answer, while Options B (4F), C (8F), and D (16F) are all incorrect.

Q99. As the quantum number increases, the energy difference between the consecutive energy levels of an atom:

• A. Increases
• B. Decreases✓
• C. Remains same
• D. Becomes infinite

Explanation: As the quantum number increases, the energy difference between consecutive energy levels of an atom decreases. This is a consequence of the quantization of energy levels in atoms, described by the Bohr model and later refined by quantum mechanics. As you move to higher quantum numbers (e.g., from n=1 to n=2, n=2 to n=3, and so on), the energy levels become closer together, and the energy difference between them becomes smaller. This is why spectral lines in atomic spectra appear closer together at higher energy levels.

Q100. The particles with mass less than of protons (among Hadrons) are called:

• A. Baryons
• B. Mesons✓
• C. Quarks
• D. Leptons

Explanation: The particles with mass less than that of protons among Hadrons are called Mesons. Mesons are composed of a quark and an antiquark, making them lighter than baryons like protons and neutrons.