Balochistan Mdcat Mock Paper 4 — Solved Past Paper with Answers

Q1. Choose the correct spelling:

• A. Exantuated
• B. Axantuated
• C. Accenchuated
• D. Accentuated✓

Explanation: To "accentuate" means to “make more noticeable and prominent” and its correct spelling is given in Option D.

Q2. Choose the correct spelling:

• A. Defnite
• B. Defanit
• C. Dafanite
• D. Definite✓

Explanation: "Definite" is the correct spelling which means “to be on point”.

Q3. The headmaster _ to speak to you.

• A. Wants✓
• B. Is wanting
• C. Was wanting
• D. Want

Explanation: “The headmaster wants to speak to you” in Option A sounds most appropriate because "headmaster" is a singular noun so we should complement it with a singular verb - eliminating Option D. The tense is simple present indicated by the verb "speak", hence the present continuous form "is wanting" in Option B is also incorrect. while the past tense form in Option C is also incorrect.

Q4. Choose the correct option: Knowledge and wisdom _ no time for connection.

• A. Has
• B. Have✓
• C. Had
• D. Are

Explanation: The context of the sentence firstly requires a verb that satisfies the need to indicate the possession of "no time for connection" by "Knowledge and wisdom." Therefore the verb forms "is/am/are" which indicate "being" are not suitable here - eliminating Option D. Moreover, since the need for "no time" is being stated as a universal statement (everlasting) i.e. started in the past and continues to be true in the present, the tense should be present perfect. Hence, the verb form should include the helping verb "Have" as indicated by Option B.

Q5. Find the error in the following sentence.

• A. They have been✓
• B. Very close friends
• C. Until they quarelled
• D. Over a petty issue.

Explanation: 'They used to be close friends but not anymore' indicates that the sentence is in the past tense hence 'have been' will not be used. 'Had been' would be the correct term here."Very close friends" correctly describes the relationship between the two people."Until they quarreled/quarrelled" correctly indicates that their friendship ended due to an argument."Over a petty issue" correctly identifies the cause of the quarrel.

Q6. I _ English since my childhood.

• A. Study
• B. Am studying
• C. Have been studying✓
• D. Studied

Explanation: Study: This option is in the present tense, which does not match the time frame "since my childhood." We need a present perfect or past perfect tense to match the time frame. 'Have been' suggests an action that started in the past, but continues in the present. Am studying: This option is also in the present tense and doesn't match the time frame mentioned. It also implies that the action is still ongoing, which may not be the case.Studied: This option is in the past tense, which does not indicate that the action started in the past and continues up to the present moment, as the sentence implies.

Q7. Some of the books on the table _ to me.

• A. Belong✓
• B. Belonging
• C. Belongs
• D. Was belong

Explanation: With pronouns like you, me, and we, 'belong' is used. "Belonging" is a gerund, which is a verb form that functions as a noun. It does not work in this context because the sentence requires a verb. "Belongs" is the singular form of the verb "to belong." Since the subject is plural ("books"), this form of the verb is not appropriate. "Was belong" is not a grammatically correct construction. The correct past tense form of "to belong" is "belonged," but the sentence is in the present tense, so this option is also not appropriate.

Q8. Have you _ the examination?

• A. Take
• B. Took
• C. Taken✓
• D. Taking

Explanation: Take - This is the present tense form of the verb, which is not appropriate for the context of the sentence.Took - This is the past tense form of the verb, which is not suitable for the present perfect tense used in the sentence.A helping verb precedes 'it' and for simple past tense, the word that should be used is 'taken': 'he has taken some other courses too.' Taking - This is the present participle form of the verb, which also does not fit the structure of the present perfect tense used in the sentence.

Q9. Father must _ left his briefcase at the office.

• A. Of
• B. Had
• C. Have✓
• D. None of these

Explanation: We use "must have" in the present perfect - the action we are describing happened, or did not happen, in the past and is still true in the present.

Q10. The excretion of hypertonic urine in humans is associated best with the:

• A. Glomerular capsule
• B. Proximal convoluted tubule
• C. Loop of Henle✓
• D. Distal convoluted tubule

Explanation: The Loop of Henle is responsible for creating a concentration gradient in the medulla of the kidney, enabling the production of hypertonic urine through the countercurrent multiplier system. This allows water to be reabsorbed in the collecting duct, concentrating the urine.

Q11. The basic functional unit of human kidney is

• A. Nephridia
• B. Loop of Henle
• C. Pyramid
• D. Nephron✓

Explanation: A nephron is a unit of structure and function in a kidney. A kidney contains about a million nephrons, each approximately 3 cm long. A nephron is a long tubule differentiated into four regions having different anatomical features and physiological role : Bowman’s capsule, proximal convoluted tubule (PCT), loop of Henle, and distal convoluted tubule (DCT). The latter opens into one of the collecting ducts. Nephridia are the excretory organs of annelids.

Q12. An enzyme that cleaves a DNA duplex molecule, at a particular base sequence, usually within or near a palindromic sequence, is called:

• A. Polymerase
• B. Helicase
• C. Restriction endonuclease✓
• D. Ligase

Explanation: The correct answer is restriction endonuclease. These enzymes are crucial in biotechnology for their ability to recognize and cleave DNA at specific sequences, often palindromic. This property allows scientists to cut DNA in a controlled manner for cloning and analysis. In contrast, polymerase synthesizes DNA, helicase unwinds DNA, and ligase joins DNA fragments. None of these other enzymes is involved in cutting DNA at specific sequences.

Q13. To clean up environmental pollutants, increase the fertility of the soil and kill insect pests, genetically engineered:

• A. Animals have been used
• B. Bacteria have been used✓
• C. Plants have been used
• D. Viruses have been used

Explanation: Genetically engineerad bacteria are used to remove environmental pollutants through bioremediation. Thay also help increase soil fertility and can be modified to control insect pests.

Q14. A technique used for correcting defective genes responsible for disease development:

• A. Gene therapy✓
• B. Cloning
• C. Tissue culture
• D. Gene sequencing

Explanation: Gene therapy is a technique that uses a gene(s) to treat, prevent or cure a disease or medical disorder.

Q15. Which one of the following technique rapidly replicates specific target fragment of DNA without cloning?

• A. DNA sequencing
• B. Genetic probe
• C. Gel electrophoresis
• D. Polymerase chain reaction✓

Explanation: PCR involves using short synthetic DNA fragments called primers to select a segment of the genome to be amplified, and then multiple rounds of DNA synthesis to amplify that segment.

Q16. Genes of interest can be selected from a genomic library by using:

• A. Cloning vectors
• B. DNA probes✓
• C. Gene targets
• D. Restriction enzymes

Explanation: A gene bank or genomic library is a complete collection of cloned DNA fragments that comprises the entire genome of an organism. Molecular probes are small DNA segments that are used to detect the presence of complementary sequences in nucleic acid samples in the genomic library. These are usually formed of 200­500 nucleotide sequences. These segments or probes are labeled either with radioactive or nonradioactive compounds. Probes with DNA sequences complementary to the gene to be isolated are used. They bind with the desired gene, making it visible and help in isolating it from the library.

Q17. The deficiency of which of the following causes severe combined immunodeficiency?

• A. Hypoxanthine-guanine transferase
• B. Xanthine oxidase
• C. PRPP synthetase
• D. Adenosine deaminase✓

Explanation: ADA deficiency leads to SCID, a group of rare, inherited disorders characterized by a severe impairment of both the T and B lymphocytes of the immune system. Adenosine deaminase is involved in the breakdown of purines, and its deficiency results in the accumulation of toxic metabolites. that are particularly harmful to developing immune cells.

Q18. All of the following protect the body against entrance of germs except:

• A. Mucus membrane
• B. WBCs
• C. Ciliated cells
• D. RBCs✓

Explanation: RBCs have no role in immunity. RBCs (red blood cells) do not protect the body against the entrance of germs. RBCs are responsible for carrying oxygen to the tissues and carbon dioxide away from the tissues. They cannot engulf or kill germs.

Q19. The type of blood cells that have a biconcave disc-like shape are:

• A. Lymphocytes
• B. Platelets
• C. Monocytes
• D. Red blood cells✓

Explanation: RBCs are biconcave, increasing surface area for oxygen transport. They are anucleate, flexible for capillary passage, and live ~120 days before breakdown and iron recycling.

Q20. The cells which play very important role in developing immunity are except:

• A. Monocytes
• B. Lymphocytes
• C. Neutrophils
• D. Thrombocytes✓

Explanation: Thrombocytes (platelets) are for clotting, not immunity. Immune defense relies on lymphocytes, neutrophils, and monocytes.

Q21. Antibodies are manufactured in:

• A. T lymphocytes
• B. Platelets
• C. Red blood cells
• D. B lymphocytes✓

Explanation: Antibodies are manufactured in B lymphocytes. B lymphocytes are a type of white blood cell that are responsible for the body's humoral immune response. The humoral immune response is the part of the immune system that fights off infection by producing antibodies. Antibodies are proteins that bind to specific antigens, which are molecules found on the surface of foreign invaders. When an antibody binds to an antigen, it triggers a cascade of events that ultimately leads to the destruction of the foreign invader. B lymphocytes are produced in the bone marrow. When a B lymphocyte encounters an antigen for the first time, it becomes activated. The activated B lymphocyte then divides and produces a clone of cells that all produce the same antibody. These cells are called plasma cells. Plasma cells secrete antibodies into the blood and lymph fluid.

Q22. Which one has the thicker walls than the others?

• A. Right atria
• B. Left atria
• C. Right ventricle
• D. Left ventricle✓

Explanation: The left ventricle has the thickest walls to generate enough force to pump oxygenated blood through the entire systemic circulation, unlike the right ventricle, which only pumps to the lungs.

Q23. Oxygenated blood is supplied to all body parts from:

• A. Right atrium
• B. Left atrium
• C. Right ventricle
• D. Left ventricle✓

Explanation: The left ventricle is the main pumping chamber of the heart, responsible for distributing oxygenated blood to the body. It receives oxygenated blood from the left atrium and pumps it through the aorta. The other options are incorrect because the right atrium and right ventricle handle deoxygenated blood, while the left atrium only transfers oxygenated blood to the left ventricle without directly supplying it to the body.

Q24. Which of the following is the function of conducting part of the respiratory system?

• A. Removal of foreign particles from incoming air.
• B. Humidifies incoming air
• C. Bring the temperature of incoming air to body temperature.
• D. All the above✓

Explanation: The conducting part of the respiratory system serves multiple functions. It not only removes foreign particles from incoming air and humidifies the air but also helps bring the temperature of incoming air closer to body temperature. These functions collectively prepare the inspired air for its journey into the lower respiratory tract, ultimately facilitating efficient and safe gas exchange in the lungs.

Q25. The pleura is a double membrane sac that envelops:

• A. Kidneys
• B. Brain
• C. Lungs✓
• D. Nasal passage

Explanation: The pleura is a specialized double-layered serous membrane that envelops the lungs and lines the thoracic cavity. The visceral pleura adheres tightly to the lung surface, while the parietal pleura lines the inner walls of the chest cavity. Between them lies the pleural cavity, which contains lubricating pleural fluid. This arrangement reduces friction during breathing and helps maintain negative pressure needed for lung expansion. Other organs such as kidneys, brain, or nasal passages are covered by different protective membranes, not pleura. Therefore, the correct answer is that pleura envelops the lungs.

Q26. The enzyme essential for the transport of CO2 as bicarbonate in the blood is:

• A. Carboxypeptidase
• B. Succinic dehydrogenase
• C. Carbonic anhydrase✓
• D. Thrombokinase

Explanation: Carbonic anhydrase is the correct enzyme responsible for the conversion of carbon dioxide (CO2) to bicarbonate (HCO3-) in the blood. This process is essential for CO2 transport in the bloodstream, helping to maintain acid-base balance in the body.

Q27. The ciliated columnar epithelial cells in humans are known to occur in:

• A. The Eustachian tube and stomach lining
• B. The bronchioles and Fallopian tube✓
• C. The bile duct and oesophagus
• D. The Fallopian tubes and urethra

Explanation: The ciliated columnar epithelial cells in humans are present in the nasal passages, oviducts (Fallopian tubes) terminal bronchioles, ventricles of the brain and central canal of the spinal cord of the embryo. The columnar ciliated epithelium consists of columnar cells which bear cilia on the free surface.

Q28. In man and mammals air passes from outside into the lungs through:

• A. Nasal cavity, larynx, pharynx, trachea, bronchi, alveoli
• B. Nasal cavity, larynx, pharynx, trachea, bronchioles, alveoli
• C. Nasal cavity, pharynx, larynx, trachea, bronchioles, bronchi, alveoli
• D. Nasal Cavity, Pharynx, larynx trachea bronchi bronchioles alveoli✓

Explanation: Air passes from nostrils into the nasal cavity where the dust particles are trapped. From nasal cavity, the air moves into pharynx which is a short, vertical tube. It further leads into two tubes, trachea and oesophagus. Larynx is the upper part of trachea. Besides forming a part of the respiratory tract, it also serves as the voice box. Trachea is a thin walled tube that extends downward through the neck. It divides into two primary bronchi which on entering the lungs divide into fine branches called bronchioles which enter the alveoli. Exchange of gases occur in alveoli.

Q29. Nucleotides sequence that is identical to its complementary strand when each is read in the same chemical direction for example i-e; 5'GATC3' 3'CATG5' these are called as:

• A. Flanking sequences
• B. Nucleotide order
• C. Palindromic sequences✓
• D. Antagonistic sequences

Explanation: Palindromic sequences occur when a sequence of base pairs reads the same in both directions on complementary strands, like 5' GATC 3' and 3' CTAG 5'. Such sequences play a crucial role in genetic engineering, particularly in restriction enzyme recognition and cutting of DNA. The other options do not fit this definition: Flanking sequences are adjacent to DNA regions of interest, Nucleotide order refers to the sequence without implying symmetry, and Antagonistic sequences is not a concept in DNA sequence terminology.

Q30. In which plant tissue does photosynthesis primarily occur?

• A. Mesophyll✓
• B. Epidermis
• C. Cortex
• D. Xylem

Explanation: Photosynthesis primarily occurs in the mesophyll tissue of plant leaves. The mesophyll tissue is specialized for photosynthesis and is located between the upper and lower epidermis of the leaf. It contains chloroplasts, the organelles responsible for capturing sunlight and carrying out photosynthesis. The mesophyll tissue consists of two main types: the palisade mesophyll, which is closely packed with elongated cells, and the spongy mesophyll, which has loosely arranged cells with air spaces for gas exchange.

Q31. The external solution having more concentration than the cell sap is known:

• A. Hypertonic solution✓
• B. Hypotonic solution
• C. Isotonic solution
• D. None of these

Explanation: The correct answer is a hypertonic solution. In osmoregulation, when a cell is placed in a hypertonic solution, the external environment has a higher concentration of solutes compared to the inside of the cell. This concentration difference causes water to move out of the cell through osmosis, leading to a decrease in cell volume and potential plasmolysis. Conversely, a hypotonic solution would cause water to move into the cell, and an isotonic solution would result in no net water movement. None of these is incorrect because the correct term for a solution with higher solute concentration than the cell sap is indeed a hypertonic solution.

Q32. The kidney of an adult frog is:

• A. Metanephros
• B. Opisthonephros
• C. Pronephros
• D. Mesonephros✓

Explanation: The mesonephros kidney is present in both the adult as well as the embryo of the frog. A mesonephros develops from the middle part of the intermediate mesoderm, posterior to each pronephros, soon after its degeneration.

Q33. Which pair is correct?

• A. Sweat – Temperature regulation✓
• B. Saliva – Sense of taste
• C. Sebum – Sexual attraction
• D. Humerus – Hindleg

Explanation: Sweat is secreted by sweat glands of skin and helps in regulating body temperature. Saliva is secreted by salivary glands and helps in digestion (carbohydrate digestion). Sebum is the waxy secretion secreted by sebaceous glands. Sebum is a fatty mildly antiseptic material that protects, lubricates, and waterproofs the skin and hair and helps prevent desiccation. Humerus is the long bone of the upper arm. It articulates with the scapula at the glenoid cavity and with the ulna and radius at the elbow.

Q34. Homeostasis is the _

• A. Tendency to change with environmental changes
• B. Tendency to resist change and maintain stability✓
• C. Disturbance in regulatory control
• D. Use of plants and animal extracts in homeopathy

Explanation: Homoeostasis is the regulation, by an organism, of the chemical composition of its body fluids and other aspects of its internal environment so that physiological processes can proceed at optimum rates. It involves monitoring changes in the external and internal environment by means of receptors and adjusting the composition of the body fluids accordingly; excretion and osmoregulation are important in this process. Example of homeostatic regulation are the maintenance of the acid-base balance and body temperature.

Q35. Which kind of therapy was given in 1990 to a four­ year­ girl with Adenosine Deaminase (ADA) enzyme deficiency?

• A. Gene therapy✓
• B. Chemotherapy
• C. Immunotherapy
• D. Radiation therapy

Explanation: Gene therapy is a technique of genetic engineering which involves the replacement of a faulty/disease-causing gene by a normal healthy functional gene. The first clinical ex-vivo gene therapy was given in 1990 to a 4­-year old girl with adenosine deaminase (ADA) enzyme deficiency. This enzyme is very important for the immune system to function and the deficiency of this enzyme can lead to severe combined immune deficiency (SCID).

Q36. In humans, the temperature regulation control center is located in:

• A. Kidneys
• B. Brain✓
• C. Lungs
• D. Liver

Explanation: The body's temperature control center is the hypothalamus which itself is part of the brain. The hypothalamus via a network of thermoreceptors can sense when you are unusually hot. If so then the hypothalamus proceeds to send signals to your sweat glands to make you sweat and cool you off. When the hypothalamus senses that you're too cold, it sends signals to your muscles that make you shiver and create warmth. This is called maintaining homeostasis. The kidneys help to maintain homeostasis by regulating the concentration and volume of body fluids. Lungs are essential for the constant gaseous exchange of O2 and CO2. The liver plays an important role in the metabolism of nutrients in your body, detoxifying drugs, storing glycogen, synthesizing plasma proteins, etc. Hence, Option B is correct.

Q37. Enzymes work by which of the following?

• A. Increasing the activation energy
• B. Reducing the activation energy✓
• C. Making exergonic reactions endergonic
• D. Making endergonic reactions exergonic

Explanation: Enzymes work by reducing the activation energy required for a chemical reaction to occur. The activation energy is the minimum energy input needed for reactant molecules to transform into products during a chemical reaction. It represents the energy barrier that must be overcome for the reaction to proceed. Enzymes facilitate reactions by providing an alternative pathway with a lower activation energy. The active site of an enzyme interacts with the substrate (reactant), bringing the reactants into close proximity and allowing the reaction to occur more easily. This reduction in activation energy accelerates the rate of the reaction and makes it more favorable under physiological conditions.

Q38. Among the following, which is the longest supportive cell?

• A. Trachea
• B. Collenchyma cells
• C. Sclereids
• D. Tracheids✓

Explanation: The trachea is an organ, not a cell, so it cannot be Option A. Collenchyma cells can reach up to 2.5mm. Sclereids are typically 1mm. Tracheids are typically 7 mm, which is the longest, hence the correct answer is Option D.

Q39. Which of the following is soluble in hot water?

• A. Starch
• B. Glycogen
• C. Amylose✓
• D. Amylopectin

Explanation: The correct answer is amylose, as it is the only option that is soluble in hot water. Amylose consists of a linear chain of glucose units connected by α-1,4-glycosidic bonds, allowing it to dissolve by forming hydrogen bonds with water. In contrast, amylopectin and glycogen are highly branched, making them too large and complex to dissolve in hot water. Starch, composed of both amylose and amylopectin, is not completely soluble due to the higher proportion of insoluble amylopectin.

Q40. As an excretory organ, liver:

• A. Detoxifies many chemical poisons
• B. Produces ammonia for excretion by the kidneys
• C. Produces urea and uric acids from the nitrogen of amino acids
• D. All of the above✓

Explanation: The liver has numerous functions in the human body, let's discuss each option one by one. A)The liver is an organ that comes into play after consumption of alcohol, as you can remember excess alcohol consumption can result in liver cirrhosis, where scarring occurs on the liver after continuous exposure to high amounts of alcohol. B&C)The urea cycle (also known as the ornithine cycle) occurs in the mitochondria of liver cells and results in the conversion of poisonous ammonia (NH3) to urea ((NH2)2CO) which is then excreted in the urine. All the above-mentioned metabolites are removed from the human body either directly (as in urea) or indirectly by further conversion into another substance. Hence, Option D is correct.

Q41. The active uptake of sodium in the ascending limb or thick loop of Henle is promoted by the action of:

• A. Aldosterone✓
• B. Thyroxine
• C. ADH (Antidiuretic hormone)
• D. Cortisone

Explanation: Aldosterone stimulates sodium reabsorption (active uptake) in the distal tubule and indirectly influences sodium handling in the thick ascending limb of Henle by promoting overall sodium retention in the nephron. (The primary driver of Na⁺/K⁺/2Cl⁻ cotransport in the thick ascending limb is the Na⁺/K⁺ ATPase energized by the electrochemical gradient, but aldosterone enhances sodium reabsorption in the distal segments.)

Q42. Which one of the following muscles is considered as “Voluntary muscle”?

• A. Smooth muscles
• B. Cardiac muscles
• C. Skeletal muscles✓
• D. Glandular muscles

Explanation: Muscles in the body are categorized into three main types: Smooth, Cardiac, and Skeletal. Skeletal muscles are classified as voluntary muscles because they are consciously controlled, allowing us to perform actions such as walking, lifting, and speaking. This contrasts with Smooth and Cardiac muscles, which are involuntary. Smooth muscles operate automatically within organs, and Cardiac muscles function independently in the heart's rhythmic contractions. Therefore, the correct answer is Option C: Skeletal muscles.

Q43. The term ‘cell’ was given by:

• A. Leeuwenhoek
• B. Robert Hooke✓
• C. Flemming
• D. Robert Brown

Explanation: The origins of the word 'cell' in the 1660s, Robert Hooke looked through a primitive microscope at a thinly cut piece of cork. He saw a series of walled boxes that reminded him of the tiny rooms, or cellula, occupied by monks.

Q44. What is an example of sperms of liverworts, mosses, and ferns that move towards archegonia, in response to nucleic acid released by the ovum?

• A. Chemotropic movement
• B. Chemonastic movement
• C. Haptonastic movement
• D. Chemotactic movement✓

Explanation: As nucleic acid is a type of chemical signal for sperm, that is why this chemical is sensed by sperm to reach the ovum. Chemotactic is the movement of an organism or entity in response to a chemical stimulus, and that is autonomic movement.

Q45. Which one of the following is a “myogenic” type of muscle?

• A. Glandular muscles
• B. Cardiac muscles✓
• C. Skeletal muscles
• D. Smooth muscles

Explanation: The term 'myogenic' refers to muscle contractions that originate from the muscle tissue itself without external stimuli from the nervous system. Cardiac muscles are 'myogenic' because they can initiate contractions autonomously due to the intrinsic pacemaker cells of the heart. This distinguishes them from skeletal muscles, which are 'neurogenic,' as they require neural input to contract. Although some smooth muscle types are 'myogenic,' the question specifies a singular type of 'myogenic' muscle, making cardiac muscle the most precise answer.

Q46. What do we call the cell surface membrane of a muscle fibre?

• A. Sarcolemma✓
• B. Plasma membrane
• C. Sarcoplasm
• D. Myofibrils

Explanation: The correct answer is Sarcolemma. The sarcolemma is the specialized cell membrane that surrounds a muscle fiber. It is crucial for communication between the nervous system and the muscle fiber, allowing the initiation of muscle contraction through electrical signal transmission. The term 'sarco-' denotes its association with muscle cells, differentiating it from the general plasma membrane found in all cell types. Option B, the 'Plasma membrane', refers to the cell membrane in general terms and does not specify its role in muscle cells. Option C, 'Sarcoplasm', is the cytoplasmic content of the muscle cell, not the membrane. Finally, Option D, 'Myofibrils', are the internal structures responsible for contraction, unrelated to the cell's surface membrane.

Q47. Which of the following neurotransmitters function, both as neurotransmitter and hormones, decreasing our perception of pain?

• A. Epinephrine
• B. Serotonin
• C. Dopamine
• D. Endorphins✓

Explanation: Neurotransmitters are chemical messengers that transmit a message from a nerve cell across the synapse to a target cell. Hormones are chemical messengers that are secreted directly into the blood, which carries them to organs and tissues of the body to exert their functions. All the options are both, a hormone as well neurotransmitters. Epinephrine, commonly referred to as Adrenaline, relaxes the airway muscles, making it easier for the person to breathe. At the same time, it constricts blood vessels, helping to improve blood pressure. It also increases the heart rate. However, it does not decrease the response to pain. Hence Option A is rejected. Serotonin, on the other hand, is used by the body to send messages between nerve cells. It appears to play a role in mood, emotions, appetite, and digestion. As the precursor for melatonin, it helps regulate sleep-wake cycles and the body clock. Since it is not used to decrease pain response, Option B is rejected. Dopamine is a neurotransmitter that plays a role in how we feel pleasure. It's a big part of our unique human ability to think and plan. However, it plays no role in the pain response. Hence Option C is rejected. Endorphins are substances produced by the nervous system to cope with pain or stress. They are often called “feel-good” chemicals because they can act as pain relievers and happiness boosters. Hence, Option D is correct.

Q48. What are the subunits of capsids?

• A. Capsomere✓
• B. Flagella
• C. Hyphae
• D. Septa

Explanation: Capsomeres are tiny subunits that make up the protein coat, referred to as the capsid. Capsomeres are known as capsid subunits, which are the outer protective covering of proteins that protect the virus's genetic material. TMV is also known as the tobacco mosaic virus. It is a type of single-stranded RNA virus.

Q49. Inactive enzyme precursors such as pepsinogen for pepsin are called as:

• A. Holoenzymes
• B. Actinases
• C. Zymogens✓
• D. Mucopolysaccharides

Explanation: Inactive enzyme precursors like pepsinogen for pepsin are commonly referred to as "zymogens" or "proenzymes." Zymogens are inactive forms of enzymes that need to undergo a specific biochemical change to become active. This transformation usually involves the removal of a peptide segment or another modification that exposes the active site of the enzyme, allowing it to catalyze reactions. In the case of pepsinogen: Pepsinogen is the inactive precursor. Pepsin is the active form of the enzyme. The conversion of pepsinogen to pepsin occurs in the acidic environment of the stomach, where the acidic conditions lead to the cleavage of a portion of the pepsinogen molecule, resulting in the activation of pepsin. Zymogens are a safety mechanism in the body to prevent the premature activation of enzymes and potential damage to tissues. They are activated at the right time and place, ensuring that enzymatic activities are tightly regulated.

Q50. When two or more clearly different phenotypes exist in the same population of species, the phenomenon is called?

• A. Replication
• B. Polymorphism✓
• C. Gene linkage
• D. Gene expression

Explanation: 'Polymorphism' means that different shapes and structures exist. 'A' is not the answer because replication is the division of the cell. 'C' is not the answer because Genetic linkage is the tendency of DNA sequences that are close together on a chromosome to be inherited together during the meiosis phase of sexual reproduction. 'D' is not the answer because Gene expression is the process by which information from a gene is used in the synthesis of a functional gene product that enables it to produce end products.

Q51. Which of these structures transports sperm from the testis to the penis?

• A. Sperm duct✓
• B. Scrotum
• C. Urethra
• D. Gamete

Explanation: The structure that transports sperm from the testes to the penis is the vas deferens. The vas deferens is a duct that is part of the male reproductive system. It extends from the epididymis, where sperm mature and are stored, through the inguinal canal, and it eventually joins with the duct from the seminal vesicle to form the ejaculatory duct. The ejaculatory duct then passes through the prostate gland and empties into the urethra, which extends through the penis. During ejaculation, sperm travel through the vas deferens to reach the urethra and are then expelled from the body through the penis.

Q52. The stretch reflex, the Golgi tendon reflex, the crossed extensor reflex, and the withdrawal reflex are included in:

• A. Stretch reflex
• B. Spinal reflex✓
• C. Golgi tendon reflex
• D. Crossed Extensor Reflex

Explanation: The spinal reflex includes the stretch reflex, the Golgi tendon reflex, the crossed extensor reflex, and the withdrawal reflex.

Q53. Proteins are polymers of:

• A. Amino acids✓
• B. Fatty acids
• C. Nucleotides
• D. None of these

Explanation: Proteins are composed of amino acids linked by peptide bonds, forming polypeptide chains that fold into specific three-dimensional structures necessary for their function. The other options are incorrect because:Fatty acids: Are components of lipids, not proteins.Nucleotides: Are building blocks of nucleic acids like DNA and RNA.None of these: Incorrect, as proteins are indeed polymers of amino acids.

Q54. Nicotinamide adenine dinucleotide is an example of:

• A. Coenzymes✓
• B. Holoenzymes
• C. None of these
• D. Both of these

Explanation: A coenzyme is defined as an organic molecule that binds to the active sites of certain enzymes to assist in the catalysis of a reaction. NAD is the most important coenzyme as well as cofactor in a eukaryotic cell. Not surprisingly, NAD and the closely related NADP are the two most abundant cofactors in eukaryotic cell.

Q55. Removal of calcium from freshly collected blood would:

• A. Cause delayed clotting
• B. Prevent clotting✓
• C. Cause immediate clotting
• D. Prevent destruction of hemoglobin.

Explanation: The correct answer is Option B: prevent clotting. Calcium ions play a critical role in the blood clotting process by enabling the conversion of prothrombin to thrombin and fibrinogen to fibrin, which are essential steps in forming a blood clot. Therefore, if calcium is removed from blood, these reactions cannot occur, effectively preventing clot formation. Option A is incorrect because delayed clotting implies that clotting will still occur, which is not the case when calcium is removed. Option C is incorrect because calcium removal will not cause immediate clotting; it will stop clotting altogether. Option D is incorrect because calcium removal does not relate to hemoglobin destruction or preservation.

Q56. The tricuspid valve is found in between:

• A. Sinus venous and right atrium
• B. The right atrium and right ventricle✓
• C. left ventricle and left atrium
• D. left ventricle and aorta.

Explanation: The tricuspid valve is found between the right atrium and the right ventricle.

Q57. Lymph differs from blood in having:

• A. No WBCs
• B. No proteins
• C. No RBCs✓
• D. None of the above

Explanation: The lymph is a whitish fluid which is derived from the interstitial fluid that circulates throughout the lymphatic system. It contains a variety of substance like proteins, glucose, water, salts, fats and white blood cells. It does not have RBCs.

Q58. RBCs do not occur in:

• A. Frog
• B. Cow
• C. Camel
• D. Cockroach✓

Explanation: Cockroaches have an open circulatory system with hemolymph but no RBCs, as oxygen transport is via tracheae.

Q59. Which body function is controlled through a positive feedback mechanism?

• A. Labor contractions✓
• B. Body temperature
• C. Insulin production
• D. Thyroxine release

Explanation: A feedback mechanism is a loop system wherein the system responds to a perturbation. The response may be in the same direction (as in positive feedback) or in the opposite direction (as in negative feedback). An example of positive feedback is uterine contractions during childbirth. The hormone oxytocin, made by the endocrine system, stimulates the contraction of the uterus. This produces the pain sensed by the nervous system. In response, more oxytocin is released, which in turn stimulates the contractions even more. This loop of the 'pain induced from contractions stimulating the release of oxytocin, and oxytocin stimulating more contraction continues with increasing intensity' still the fetus is born. This is a positive feedback loop; hence, Option A is correct.

Q60. Which one of the following is common to all neurons?

• A. A cell body which contains a nucleus✓
• B. Presence of Nodes of Ranvier
• C. A thick myelin sheath
• D. Presence of Schwann cells

Explanation: The cell body (soma) is the main nutritional and metabolic center of all neurons, containing the nucleus and responsible for biosynthesis of proteins and energy for neuronal function.

Q61. Neurons are cells adapted for the rapid transmission of electrical impulses. To do this, they have long, thin processes called:

• A. Axons✓
• B. Dendrites
• C. Myelin sheath
• D. Schwann cell

Explanation: Axons are long, thin processes that transmit neural impulses from the cell body to other neurons or effector cells. Dendrites are short extensions for receiving signals. Schwann and myelin sheath provide insulation and increase conduction speed, but do not transmit impulses themselves.

Q62. Which of the following sections of a sarcomere does not shorten during contraction?

• A. I band
• B. H zone
• C. A band✓
• D. None of these

Explanation: Even though the 'I band' and the 'H zone' change in length, the 'A band' remains the same in length. 'A' is not the answer because the I band reduces in size. 'B' is not the answer because the H zone disappears during contraction.

Q63. When resources gets scarce, the population growth?

• A. Increases exponentially
• B. Slows down✓
• C. Remains constant
• D. None of these

Explanation: When resources are abundant, populations can grow rapidly. However, as resources become scarce, the growth rate slows due to increased competition for those resources. This is known as density-dependent regulation. The environment's carrying capacity limits the population size. While exponential growth is impossible under these conditions, population growth may either slow or decline. Therefore, the correct answer is that population growth slows down. Options suggesting exponential increase or constant growth are incorrect because they fail to consider the limiting role of scarce resources.

Q64. Which of the following is not associated with the process of respiration?

• A. Lungs
• B. Gills
• C. Bladder✓
• D. Trachea

Explanation: The bladder is not directly associated with the process of respiration. The bladder is an organ found in the urinary system of vertebrates, including humans. Its primary function is to store urine temporarily until it is expelled from the body during the process of urination. Urine is produced in the kidneys as a waste product of metabolism and has no direct involvement in the respiration process.

Q65. Which of the following is made up of an afferent pathway from a receptor and an efferent pathway to an effector?

• A. Nerve cell
• B. Reflex arc✓
• C. Receptor cells
• D. Mixed nerve

Explanation: The diagram shows a reflex arc, which consists of a receptor, an afferent neuron, an efferent neuron, and the effector.

Q66. The types of gametes produced by two pairs of chromosomes can be?

• A. 2
• B. 4✓
• C. 6
• D. 8

Explanation: Humans have 2 pairs of chromosomes. So for each pair, there are two options available. 2C1 x 2C1= 2 x 2 = 4 When two pairs of chromosomes undergo meiosis, the different combinations of maternal and paternal chromosomes lead to four different types of gametes. This is due to the independent assortment of homologous chromosomes during meiosis I. Each homologous pair aligns independently during metaphase I, leading to a random distribution of maternal and paternal chromosomes into the resulting gametes. As a result, four different combinations of alleles are possible for each pair of chromosomes.

Q67. Which of the following statements about chordates is true?

• A. They are protostomes
• B. All chordates are vertebrates
• C. They lack a coelom
• D. Their anus forms from the blastopore✓

Explanation: Chordates are deustromes so the answer cannot be Option A. All vertebrates are chordates but not all chordates are vertebrates so the answer cannot be Option B. All chordates have a coelom so the answer cannot be Option C and their anus is formed first from blastopore so the answer is Option D.

Q68. A common polyhedral capsid shape of viruses is a _.

• A. Complex
• B. Spherical
• C. Icosahedral✓
• D. Helical

Explanation: Among viruses, the most common polyhedral capsid shape is icosahedral, which consists of 20 triangular faces forming a highly stable and efficient structure. Helical viruses, although common, have a spiral structure rather than flat faces. Spherical viruses appear round due to their envelope, not because of a true polyhedral capsid. Complex viruses, such as bacteriophages, have mixed structural features that do not fit simple polyhedral forms. Therefore, when considering a classic polyhedral capsid, the correct answer is icosahedral.

Q69. HDL is synthesized in:

• A. Adipose tissue
• B. Liver
• C. Intestine
• D. Liver and intestine✓

Explanation: The correct answer is 'Liver and intestine'. HDL is synthesized both in the liver and the intestines. The liver is the primary site of HDL synthesis, where hepatocytes produce and release HDL particles into the bloodstream. The intestines also play a role by synthesizing HDL in the enterocytes of the small intestine. Together, these organs are essential for the production and regulation of HDL. This is why option D is correct. Options A, B, and C are incorrect because they do not fully account for the synthesis locations of HDL.

Q70. In Anaerobic respiration, how much % of the energy, present within the chemical bond of glucose, is converted into ATP?

• A. 2✓
• B. 4.5
• C. 5.6
• D. 7.7

Explanation: In Anaerobic respiration only 2% of the energy present within the chemical bond of glucose is converted into ATP.

Q71. A _ is a junction between two neurons or between a motor neuron and a muscle cell.

• A. Impulse
• B. Synapse✓
• C. Axon
• D. Cleft

Explanation: In the nervous system, a synapse is a structure that permits a neuron (or nerve cell) to pass an electrical or chemical signal to another neuron or to the target effector cell. It can be visualized as a gap between two neurons; however, that gap isn't referred to as a synapse, but rather the gap, also known as the synaptic cleft, alongside the end of the pre-synaptic neuron and the start of the post-synaptic neuron is collectively known as the synapse. Option B is hence correct.

Q72. Which one of the following represents the changes that occur in the ovary and the uterus approximately every 28 days involving ovulation with the breakdown and loss of the lining of the uterus?

• A. Ovulation
• B. Menstrual cycle✓
• C. Uterine cycle
• D. Embryo formation

Explanation: Changes that occur in females in ovary and uterus every 28 days is collectively referred to as menstrual cycle.

Q73. Which of the following diseases is sexually transmitted?

• A. Tuberculosis
• B. AIDS✓
• C. Dengue fever
• D. Cholera

Explanation: Acquired immunodeficiency syndrome (AIDS) is a chronic, potentially life-threatening condition caused by the human immunodeficiency virus (HIV). By damaging your immune system, HIV interferes with your body's ability to fight infection and disease. You can get HIV from contact with infected blood, semen, or vaginal fluids. Most people get the virus by having unprotected sex with someone who has HIV. Another common way of getting it is by sharing drug needles with someone who is infected with HIV. Hence, Option B is correct.Tuberculosis is caused by bacteria that spread from person to person through microscopic droplets released into the air. This can happen when someone with the untreated, active form of tuberculosis coughs, speaks, sneezes, spits, laughs, or sings. Hence, Option A is incorrect. When a mosquito bites a person infected with a dengue virus, the virus enters the mosquito. Then, when the infected mosquito bites another person, the virus enters that person's bloodstream and causes an infection. Hence, Option C is incorrect. A person can get cholera by drinking water or eating food contaminated with cholera bacteria. In an epidemic, the source of the contamination is usually the feces of an infected person that contaminates water or food. Hence, Option D is incorrect.

Q74. According to lvanovski, what are soluble living germs?

• A. Bacteria
• B. Viruses✓
• C. Fungi
• D. Both A and B

Explanation: According to Ivanovski, the term "soluble living germs" refers to the infectious agent responsible for causing the disease tobacco mosaic disease (TMD). Dimitri Ivanovski, a Russian botanist, conducted pioneering research in the late 19th century to investigate the cause of TMD, which affects tobacco plants.

Q75. If both the alleles are the same with respect to genes, then they are called?

• A. Heterozygous
• B. Unicellular
• C. Homozygous✓
• D. None of these

Explanation: If both of the two gametes (sex cells) that fuse during fertilization carry the same form of the gene for a specific trait, the organism is said to be 'homozygous' for that trait. 'A' is not an answer because heterozygous refers to having inherited different forms of a particular gene from each parent. 'B' is not the answer because the term unicellular refers to the state of a cell.

Q76. As long as two species occupy different niches, there is:

• A. Competition
• B. No competition✓
• C. Gene linkage
• D. Polymorphism

Explanation: The correct answer is that there is no competition when two species occupy different niches. A niche defines how a species interacts with its environment, including its habitat and resource use. When niches differ, species reduce direct competition by exploiting distinct resources or ecological strategies. Therefore, occupying different niches allows coexistence without the need for competing for the same resources. The other options are incorrect because they pertain to genetic concepts (gene linkage and polymorphism) or misunderstand the ecological principle of niches (competition).

Q77. The type of plastids found in the roots of plants are _.

• A. Chloroplasts
• B. Chromoplasts
• C. Leucoplasts✓
• D. All of these options are correct

Explanation: c) Leucoplasts:Leucoplasts are a third type of plastid found in plant cells. They are non-pigmented and play a role in storing or synthesizing various substances. There are different types of leucoplasts, including amyloplasts (which store starch), elaioplasts (which store oils and lipids), and proteinoplasts (which store proteins). These plastids are commonly found in non-photosynthetic tissues like roots, seeds, and tubers, where they assist in various storage functions.

Q78. For attachment, the rabies virus binds to a:

• A. Complement receptor
• B. Integrin ICAM-1
• C. Acetylcholine receptor✓
• D. Epidermal growth factor receptor

Explanation: To clarify, the attachment of the rabies virus to host cells involves interactions between viral glycoproteins and specific receptors, and in the case of the rabies virus, one of the receptors used for attachment is the nicotinic acetylcholine receptor (nAChR). This receptor is normally associated with nerve signal transmission but is repurposed by the virus for attachment, facilitating its entry into host cells.

Q79. Which of the following hormones of the pituitary gland regulates the menstrual cycle?

• A. Follicle Stimulating hormone and Estrogen
• B. Luteinizing hormone and Estrogen
• C. Follicle Stimulating hormone and Luteinizing hormone✓
• D. Estrogen and Progesterone

Explanation: Four hormones are primarily active in the menstrual cycle namely; FSH: Secreted by the anterior pituitary gland. In women, FSH helps control the menstrual cycle and stimulates the growth of eggs in the ovaries. LH: Secreted by the anterior pituitary gland. It also triggers the release of an egg from the ovary in the process known as 'ovulation'. (Option C is therefore correct since both; FSH and LH are produced by the pituitary gland)Estrogen: The ovaries, which produce the eggs, are the main source of estrogen from your body. In females, it helps to develop and maintain both the reproductive system and female characteristics, such as the breasts and pubic hair. Estrogen causes the uterine lining to grow and thicken to prepare the uterus for pregnancy. Progesterone: The corpus luteum in the ovaries, and the placenta, after the embedding of the zygote in the uterus lining, tend to release progesterone. The hormone prepares the endometrium lining to receive and nourish a fertilized egg. If pregnancy does not occur, estrogen and progesterone levels decrease. The decrease in progesterone triggers menstruation or shedding of the lining. Once the lining is completely shed, a new menstrual cycle begins.

Q80. Hemophilia occurs because of:

• A. Mutation in an autosome
• B. Mutation of Y-chromosome
• C. Mutation of X-chromosome✓
• D. Deficiency of iron

Explanation: Hemophilia is a bleeding disorder that slows the blood clotting process. Hemophilia A and hemophilia B are inherited in an X-linked recessive pattern. The genes associated with these conditions are located on the X chromosome, which is one of the two sex chromosomes. In males (who have only one X chromosome), one altered copy of the gene in each cell is sufficient to cause the condition. In females (who have two X chromosomes), a mutation would have to occur in both copies of the gene to cause the disorder. Because it is unlikely that females will have two altered copies of this gene, it is very rare for females to have hemophilia. A characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons. So, the correct answer is 'Mutation of X-chromosome'.

Q81. Which traits are most likely to affect men than women?

• A. X linked recessive✓
• B. X linked dominant
• C. Autosomal dominant
• D. Autosomal recessive

Explanation: Every cell in the human body has 23 pairs of chromosomes. One of these pairs is made up of 2 sex chromosomes. These are called X and Y chromosomes. One of these is inherited from the mother and the other from the father. Females have 2 X chromosomes, while males have 1 X and 1 Y chromosome. In females, the normal, unchanged, or healthy gene can override a recessive mutation so the disorder is suppressed. Disorders linked to X-linked recessive mutations usually only happen in females when they have 2 copies of the recessive mutation (1 on each X chromosome). In this case, there's no dominant "healthy" gene to override it. But, in males, there's only 1 X chromosome and if it has the recessive mutation, they will have the disorder. Recessive X-linked disorders tend to be more common in males because it's less likely that a female will get 2 copies of the recessive mutation. In females, dominant X-linked mutations will always cause the disorder. This is because the mutated gene takes over or overrides the genes on the healthy X chromosome. In males, remember, there's only 1 X chromosome and if it has the dominant mutation, they'll have the disorder. Mutations on autosomal chromosomes (22 pairs of chromosomes other than the sex chromosomes) will have an equal effect on both males and females.

Q82. Which cells secrete flexible, elastic, non-living matrix collagen that surrounds the cartilage?

• A. Osteocytes
• B. Osteoclasts
• C. Chondrocytes✓
• D. Osteoblasts

Explanation: 'Chondrocytes' are the first chondroblast cells that produce the collagen extracellular matrix (ECM) and then get caught in the matrix. Options A, B, and D are wrong because all three cells are related to bone, whereas option C is related to cartilage.

Q83. Which of the following statements was not explained by Darwin's theory?

• A. The significance of minute variations
• B. Presence of vestigeal or useless organs
• C. The presence of over specialized organs
• D. All of the above✓

Explanation: 'Darwin's theory' was based on variations, struggle, natural selection, and differential reproduction. Thus, Darwin maintained that living organisms show variations and the variant best suited is selected by nature to 'reproduce'. Thus, vestigial or over-specialized organs are not expected. Vestigial organs might arise by progressive disuse and over-specialized organs by progressive use. Both of these are not a Darwinian view. Darwin's view is that if something is useful it will be selected to be passed on to the next generation and that's it. Not that, that organ will become overspecialized or vestigial, if not required. In the same way, minute variations, which do not confer any major advantage to the organism in a particular environment are useless and will not affect the evolutionary process.

Q84. In uncompetitive inhibition, the inhibitor binds with:

• A. Enzyme
• B. Substrate
• C. E-S complex✓
• D. All of these options are correct

Explanation: c) ES-complex:This option is correct. Uncompetitive inhibition is characterized by the binding of the inhibitor to the enzyme-substrate complex (ES-complex). The inhibitor recognizes the ES-complex and binds specifically to it, altering the enzyme's active site's conformation. This binding prevents the release of the product and, in some cases, can also prevent the release of the enzyme from the complex.

Q85. Out of 31 pairs of spinal nerves, how many are pairs of coccygeal nerves?

• A. 1✓
• B. 12
• C. 15
• D. 10

Explanation: In total, there are 31 pairs of spinal nerves grouped regionally by spinal region. More specifically, there are eight cervical nerve pairs (C1-C8), twelve thoracic nerve pairs (T1-T12), five lumbar nerve pairs (L1-L5), 5 sacral (S1-S5), and a single coccygeal nerve pair. Options B, C, and D are incorrect.

Q86. What is the major cell infected by the AIDS HIV Virus?

• A. Lymphocytes
• B. Cancer cells
• C. Stem cells
• D. T lymphocytes✓

Explanation: HIV primarily targets a type of cell in the immune system called the CD4+ T cell. However, many types of these cells exist, and they are not all equally susceptible to infection by HIV HIV also affects central nervous system Option A,B and C are incorrect

Q87. The hinge joint and ball and socket joints are the types of

• A. Freely movable joints✓
• B. Slightly movable joints
• C. Immovable joints
• D. None of these

Explanation: The hinge joint shows movement in one plane while the ball and socket joints allow movement in three planes. Both of them are freely moveable joints since they allow large movements.

Q88. _ alleles both have an effect on the phenotype of a heterozygous organism:

• A. Dominant
• B. Recessive
• C. Co-dominant✓
• D. Multiple

Explanation: In a Co-dominant scenario, the two different alleles of the gene contributing to a particular characteristic would express themselves in a collaborative manner, producing a phenotype that is a combination of the two different phenotypes coded by the respective alleles.

Q89. When both the alleles of a gene pair are same, the organism is said to be:

• A. Heterozygous
• B. Genotype
• C. Homozygous✓
• D. Phenotype

Explanation: An allele is one of two, or more, forms of a given gene variant. Each person has at least two alleles for a specific gene. If they are the same then the organism is called Homozygous for that gene. (Option B is correct) And if they are different, they are called heterozygous for that allele.A genotype is an organism's set of heritable genes that can be passed down from parents to offspring. A phenotype is an individual's observable traits, such as height, eye color, and blood type.

Q90. The reduction of nitrile produced a compound of formula C3H7NH2. Which one of the following compounds would be produced if the same nitrile was hydrolyzed by heating with dilute hydrochloric acid?

• A. CH3CONH2
• B. CH3CH2NH2
• C. (CH3)2CHCO2H
• D. CH3CH2CO2H✓
• E. CH3CH2OH

Explanation: The hydrolysis of nitrile produces carboxylic acid. Since the number of carbons given in our question is 3 so the correct answer should be a carboxylic acid with 3 carbons and that is option D. A and B are amines, hence wrong. C is wrong because it has extra carbon. E is wrong because it is alcohol.

Q91. Which of the following reaction has greater Kp than Kc?

• A. 2NO + Cl2 <--> 2NOCl
• B. 2SO2 + O2 <--> 2SO3
• C. 2NOCl <--> 2NO + Cl2✓
• D. N2 + 3H2 <--> 2NH3

Explanation: When the volume of products is greater than the volume of reactants, then Kp> Kc. From the options above, only Option C has more volume of gases at the product side as compared to the reactant side. We concluded this from the mole ratio of the equation which is 3 on the product side against 2 on the reactant side.

Q92. According to the law of mass action, "The rate of chemical reaction" is proportional to the:

• A. The Amount of product formed
• B. Product of the molar concentration of the reactant✓
• C. The initial concentration of reactant
• D. Catalyst

Explanation: The law of mass action states that reaction rate depends on how frequently reactant molecules collide. This frequency increases with their molar concentrations, so the rate is proportional to their product. Thus, option B correctly describes the law of mass action.

Q93. The relationship between quantum number n and l is:

• A. n = l - 1
• B. l = n - 2
• C. l = n - 1✓
• D. n = l - 2

Explanation: The principal quantum number, n, describes the energy of an electron and the most probable distance of the electron from the nucleus. In other words, it refers to the size of the orbital and the energy level the electron placed in it. The number of subshells describes the shape of the orbital. The relationship b/w n and l is l=n-1, i.e, if n=1 then l=0.

Q94. Purification of table salt (NaCl) by passing HCl gas through its saturated aqueous solution is an example of:

• A. Law of mass action
• B. Hess’s law
• C. Common ion effect✓
• D. Henry’s law

Explanation: In saturated solution of NaCl,equillibrium is established between ions and unionised NaCl.NaCl ⇌ Na+ + Cl-When HCl gas is passed through a saturated solution of NaCl, it is completely dissociated to form H+ and Cl- ions.HCl —>H+ + Cl-Cl- ion is common to both electrolytes, hence Cl- ion concentration in solution increases. According to Le-chatelier’s principle, the position of the equilibrium gets shifted to the left side. Hence the ionization of NaCl gets suppressed and the deposition of NaCl takes place.

Q95. How will the equilibrium of the following reaction be affected if additional nitrogen is added?N2(g) + 3H2(g) ⇌ 2NH3(g)

• A. It will be shifted to the right.✓
• B. It will be shifted to the left.
• C. It will be unaffected.
• D. The effect on the equilibrium can not be determined without more information.
• E. Less NH3 will be produced.

Explanation: If N2 is added, the equilibrium will be shifted to the right side as N2 is the reactant. According to Le Chatelier, increasing the concentration of the reactants favour the forward reaction.

Q96. In which of the following will water evaporate earlier?

• A. Cup
• B. Saucepan✓
• C. Glass
• D. Small bowl

Explanation: The rate of water evaporation depends on various factors such as the surface area exposed to air, temperature, humidity, and airflow. In general, water will evaporate more quickly in conditions where these factors promote evaporation. If we assume that the initial conditions (temperature, humidity, etc.) are the same for all containers, then the primary factor influencing the rate of evaporation would be the surface area exposed to air. Larger surface areas allow for more water molecules to be in contact with the air, promoting faster evaporation. A wide saucepan typically has a larger surface area compared to a cup, glass, or small bowl. Therefore, under similar conditions, water is likely to evaporate earlier from a saucepan than from the other containers.

Q97. Different kinds of atoms of the same element are called isotopes having different _ but same _ properties.

• A. Physical, atomic
• B. Physical, chemical✓
• C. Chemical, physical
• D. Chemical, atomic

Explanation: Different kinds of atoms of the same element, which have the same number of protons but different numbers of neutrons (resulting in different masses), are called isotopes. Isotopes of the same element have different physical properties, such as different atomic masses and, in some cases, different nuclear stabilities. However, isotopes of the same element have the same chemical properties. This is because chemical properties are primarily determined by the number and arrangement of electrons, which is determined by the number of protons in the nucleus. Since isotopes of the same element have the same number of protons, they exhibit the same chemical behavior.

Q98. The order of reaction for which half-life is inversely proportional to the concentration of reaction is?

• A. Second Order✓
• B. Zero Order
• C. First Order
• D. Third Order

Explanation: A second-order reaction is a type of chemical reaction that depends on the concentrations of a one second-order reactant or two first-order reactants. This reaction proceeds at a rate proportional to the square of the concentration of one reactant, or the product of the concentrations of two reactants.

Q99. The unit used to express the relative atomic mass is called?

• A. Gram unit
• B. Avogadro's number
• C. Atomic mass
• D. Atomic mass unit✓

Explanation: One atomic mass unit (1amu) is a mass unit equal to exactly one-twelfth (1/12th) the mass of one atom of carbon-12 isotope, which is the scale used to compare atomic masses. So, the unit used to express relative atomic mass is amu. Thus, option D is correct.

Q100. Which of the following properties does not belong to Gases?

• A. Indefinite volume
• B. Indefinite shape
• C. Low density
• D. Strong interactions✓

Explanation: Strong interactions as gases have weak interactions since the particles move quickly in random motion and move far apart from each other which results in weak intermolecular forces of attraction.

Q101. Primary Alcohol is produced by reactions of Grignard's reagent with _ followed by hydrolysis in an acidic medium.

• A. Carbon dioxide
• B. Formaldehyde✓
• C. Acetaldehyde
• D. Ketone
• E. Methyl chloride

Explanation: The Grignard Reaction involves the addition of an organomagnesium halide (Grignard reagent) to carbonyl compounds. When Grignard reagents react with formaldehyde, a primary alcohol is produced upon hydrolysis in an acidic medium. Formaldehyde is unique as it is the simplest aldehyde, thus allowing the formation of a primary alcohol. Other aldehydes and ketones lead to secondary and tertiary alcohols, respectively. Carbon dioxide reacts with Grignard reagents to form carboxylic acids, not alcohols, and methyl chloride does not react to form an alcohol.

Q102. Which of the following is TRUE regarding Methyl Alcohol?

• A. It is a colorless, volatile, thin liquid with specific gravity 0.796 at 15°C.✓
• B. It is used for low-temperature thermometers and as a fuel substitute.
• C. It is extensively used in the formation of different beverages.
• D. It is used as a base for perfumes.
• E. It is used as an antiseptic and disinfectant.

Explanation: Methyl Alcohol, also known as methanol, is a colorless, volatile, and thin liquid with a specific gravity of 0.796 at 15°C. This makes Option A the correct choice. Methyl Alcohol is primarily used as an industrial solvent and antifreeze, and is not suitable for consumption or use in perfumes due to its toxicity. Options B and C describe Ethanol, which is used in thermometers and beverages. Option D describes esters, often used in perfumes. Option E describes Phenol, which is used as an antiseptic and disinfectant.

Q103. Which type of isomerism depends on the distribution of carbon atoms on each side of the functional group?

• A. Structural isomerism
• B. Functional isomerism
• C. Chain isomerism
• D. Metamerism✓

Explanation: This type of isomerism arises due to the presence of different alkyl chains on each side of the functional group.Structural isomer is a type of isomerism that uses the same formula but different structures. Functional isomerism is a type of isomerism in which two structures have the same formula but different functional groups. Chain isomers have the same molecular formula, but the way their carbon atoms are joined together differs from isomer to isomer.

Q104. Which one of the following molecules has the shortest distance of carbon atoms?

• A. CH3 - CH3
• B. CH2 = CH2
• C. CH ≡ CH✓
• D. CH3 - CH2 - CH3
• E. CH2 = CH2 - CH3

Explanation: The bond lengths of ethane, ethene and ethyne are 154pm, 133pm and 120pm respectively. Hence, ethyne has shortest bond length.

Q105. Which pair has 1 electron in its ‘s’ orbital?

• A. Li and Fe
• B. Na and Cr✓
• C. K and Mn
• D. H and He

Explanation: - Sodium (Na) has 11 electrons in its electron configuration [1s² 2s² 2p⁶ 3s¹]. One electron occupies the 's' orbital. - Chromium (Cr) has 24 electrons in its electron configuration [1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹ 3d⁵]. In the case of chromium, the electron configuration shows that one electron occupies the 's' orbital.

Q106. A reaction with a tendency of occurring in forward and backward direction simultaneously is termed as

• A. Irreversible
• B. Unidirectional
• C. Multidirectional
• D. Reversible✓

Explanation: These two reactions are occurring simultaneously, which means that the reactants are reacting to yield the products, as the products are reacting to produce the reactants. This process continues over and over again, representing a reversible reaction.

Q107. Rate constant is denoted by?

• A. k✓
• B. kv
• C. kf
• D. ks

Explanation: The correct answer is "k" as it is the standard symbol used to represent the rate constant in chemical kinetics. The rate constant is a crucial parameter that connects the rate of a chemical reaction to the concentrations of the reactants. It provides insights into the speed and dynamics of the reaction under specific conditions. The other options, such as "kv", "kf", and "ks", are not standard symbols for the rate constant, although "kf" might sometimes be used to specifically denote a forward reaction rate constant, it is not the general symbol.

Q108. Structure of ice is similar to which of the following?

• A. Liquid water
• B. Diamond✓
• C. Graphite
• D. Sucrose

Explanation: The correct option is B. The structure of ice is similar to the structure of DIAMOND. Ice and diamond are both examples of crystalline structures. In ice, water molecules are arranged in a regular, repeating pattern forming a crystal lattice. Each water molecule is bonded to four neighboring water molecules through hydrogen bonds. This arrangement gives ice its solid and stable structure. Similarly, a diamond is also a crystalline structure, where carbon atoms are arranged in a three-dimensional lattice. Each carbon atom is covalently bonded to four other carbon atoms, creating a very rigid and stable structure.

Q109. Which of the following is an assumption of the kinetic model of an ideal gas?

• A. Gas is at high pressure
• B. Collision between particles are elastic✓
• C. There are weak forces of attraction between particles in gas
• D. Total energy of particles is proportional to the temperature

Explanation: The five main postulates of the KMT are as follows: (1) The particles in a gas are in constant, random motion.(2) The combined volume of the particles is negligible.(3) The particles exert no forces on one another.(4) Any collisions between the particles are completely elastic.(5) The average kinetic energy of the particles is proportional to the temperature in kelvin.

Q110. Which of the following exerts the lowest vapour pressure?

• A. Chloroform
• B. Methanol
• C. Water✓
• D. Ethanol

Explanation: The stronger the intermolecular forces, the lower the vapor pressure. Water has the strongest forces amongst these options (4 H-bonds), hence it will have the lowest vapor pressure.

Q111. Linear combination of atomic orbitals (LCAO) results in the formation of:

• A. Sigma bond
• B. Pi bond
• C. Bonding molecular orbitals only
• D. Bonding and antibonding molecular orbitals✓
• E. All of these options

Explanation: According to Molecular Orbital Theory (MOT), two atomic orbitals overlap resulting in the formation of molecular orbitals. Number of atomic orbitals overlapping together is equal to the molecular orbital formed. The two atomic orbital thus formed by LCAO (linear combination of atomic orbital) in the same phase or in the different phase are known as Bonding Molecular Orbital (BMO) and Antibonding Molecular Orbitals (ABMO) respectively.

Q112. The raindrop acquires a spherical shape and ink spread over blotting paper due to:

• A. Surface tension✓
• B. Adhesive forces
• C. Viscosity
• D. Polarity
• E. Latent heat of vaporization

Explanation: A raindrop falling through the atmosphere forms a roughly spherical structure due to the surface tension of water. This surface tension is the “skin” of a body of water that makes the molecules stick together. The cause is the weak hydrogen bonds that occur between water molecules.

Q113. Ethanol, when reacted with PCI5 , gave A, POCl3, and HCI. A reacts with AgNO2 to form B and AgCl. A and B are respectively:

• A. C2H5Cl and C2H5OC2H5
• B. C2H6 and C2H5OC2H5
• C. C2H5Cl and C2H5NO2✓
• D. C2H6 and C2H5NO2
• E. C2H6 and C2H6NO

Explanation: The sequence of reactions begins with ethanol (C2H5OH) reacting with phosphorus pentachloride (PCl5), resulting in the formation of ethyl chloride (C2H5Cl), phosphorus oxychloride (POCl3), and hydrochloric acid (HCl). The ethyl chloride then reacts with silver nitrate (AgNO2), producing nitroethane (C2H5NO2) and silver chloride (AgCl). The correct products for A and B in the sequence are thus ethyl chloride and nitroethane, respectively. The other options involve incorrect products, such as diethyl ether, ethane, or incorrect formulas, and do not match the reaction steps provided.

Q114. The transition element which doesn't show variable valency?

• A. Cu
• B. Sc
• C. Zn✓
• D. Cr

Explanation: The answer to the question should be option C because Zinc does not show the variable valency as elements of the d-block. After all, the d-orbital is full. Its outer electronic configuration is 3d^10 4s^2 So, they tend to lose only 2 electrons from its outermost shell. Hence, only show a valency of +2 and no variable valency.

Q115. During oxidation process, oxidation number of an element:

• A. Decreases
• B. Increases✓
• C. Remains constant
• D. Both decreases and increases

Explanation: A loss of negatively charged electrons corresponds to an increase in oxidation number, while a gain of electrons corresponds to a decrease in oxidation number. Therefore, the element or ion that is oxidized undergoes an increase in oxidation number.

Q116. Which of the following has lowest e/m ratio?

• A. Li+2
• B. H+
• C. He+
• D. Be✓

Explanation: The charge to mass ratio is called the e/m ratio. e/m ratio is a physical quantity, widely used in the electrodynamics of charged particles. All we have to do in this scenario is divide the net charge of the species given in the options by their respective relative atomic mass. As Be is practically neutral, it has no net charge or a charge of zero making its e/m zero as well; the lowest out of the options provided.

Q117. Prussian blue is:

• A. K2Fe[FeCN6]
• B. K4[FeCN6]
• C. Fe4[Fe(CN)6] 3xH2O✓
• D. K3FeCN6

Explanation: This is the following solution:

Q118. Variable valency is generally exhibited by:

• A. Normal elements
• B. Transition elements✓
• C. Metallic elements
• D. None of them

Explanation: Transition elements show variable oxidation states because: 1. The energy difference between 3d and 4s orbitals is very small. 2. Electrons of both 3d and 4s orbitals participate in bond formation (however, electrons are first lost from the 4s orbital).

Q119. Which type of movement is shown by the atoms of the solid?

• A. Translational motion
• B. Vibrational motion✓
• C. Rotational motion
• D. Linear motion

Explanation: The correct option is B. Solid has a fixed shape and a fixed volume because the particles can move only a little. The particles vibrate back and forth but remain in their fixed positions. As a solid is heated, the particles vibrate faster and faster until they have enough energy to break away from their fixed positions.

Q120. The rate of diffusion of liquids is _ than gases.

• A. Lower✓
• B. Higher
• C. Equal to
• D. All of these options are correct

Explanation: Diffusion is the intermixing (movement) of molecules. When looking at diffusion you must look at two factors: forces of attraction and kinetic energy of molecules. Liquids have a stronger force of attraction than gases, and liquids have less KE than gases. This is because gas particles are further apart compared to liquid particles and move faster. This makes liquids have a lower rate of diffusion than gases.

Q121. Real gas is converted to ideal gas at:

• A. Low temperature, high pressure
• B. High temperature, high pressure
• C. Low temperature, low pressure
• D. High temperature, low pressure✓

Explanation: At high temperatures and low pressure, molecules of a gas are far apart, with minimal forces of attraction between them. This causes real gases to behave much like an ideal gas.

Q122. Ethyl iodide and n-propyl iodide are allowed to undergo the Wurtz reaction. The alkane which will not be obtained in this reaction is:

• A. Butane
• B. Propane✓
• C. Pentane
• D. Hexane

Explanation: In the Wurtz reaction, two alkyl halides react with sodium to form a higher alkane. Ethyl iodide (C2H5I) + n-propyl iodide (C3H7I) can give butane (C2+C2), pentane (C2+C3), and hexane (C3+C3). Propane (C3H8) cannot be formed because no combination of these two halides produces it.

Q123. Harmful and undesirable reaction of a metal when exposed to the atmosphere or any chemical agent is known as:

• A. Allotropy
• B. Electroplating
• C. Collision
• D. Cracking
• E. Corrosion✓

Explanation: The harmful and desirable reaction which occurs due to oxidation of the metal exposed to the surrounding air is called corrosion.

Q124. Purification of bauxite whose major impurity Is silica (SiO2) is carried out through:

• A. Baeyer’s Method
• B. Hall’s Method
• C. Serpek’s Method✓
• D. Contact Method
• E. Electrolytic Method

Explanation: Serpek's method is used for the purification of bauxite if it contains an excess amount of silica (SiO2). The powdered bauxite is mixed with carbon and heated up to 1800˚C and a current of nitrogen is passed, aluminum nitride is obtained. Silica is converted into silicon (Si).

Q125. Sigma bond is formed by:

• A. Transferring the electrons
• B. Head-on overlapping of atomic orbitals✓
• C. Mutual but unequal sharing of electrons
• D. Parallel overlapping of atomic orbitals
• E. All of these options

Explanation: The sigma bond, the strongest type of covalent bond, is formed by the head-on overlapping of atomic orbitals. This overlap allows for maximum electron density between the two bonding nuclei, resulting in a stable bond. In contrast, ionic bonds are formed by the transfer of electrons (Option A), polar covalent bonds arise from mutual but unequal sharing of electrons (Option C), and pi bonds result from the parallel overlapping of atomic orbitals (Option D). Thus, Option B is the only correct description for sigma bond formation.

Q126. The isomers must have the same:

• A. Physical properties
• B. Molecular Formula✓
• C. Structural Formula
• D. Chemical properties
• E. Both Molecular and Structural formula

Explanation: Isomers have the same molecular formula but different structures.

Q127. CH3CH2CH2COCH3 is the functional isomer of:

• A. CH3CH2CH2CH2CHO✓
• B. CH3CH2CH2CH2OH
• C. CH3CH2COCH2CH3
• D. CH3 - (CH)2 COCH2CH3

Explanation: CH3CH2CH2COCH3 and CH3CH2CH2CH2CHO have the same number of atoms for the constituent elements, Carbon, Oxygen, and Hydrogen. However, the second requirement of a 'Functional Isomer' is that the functional groups, of the two isomers, must be different and since, in this case, we have a ketone functional group and an aldehyde functional, both compounds can be positively termed as 'Functional Isomers' of each other.Thus, option A is correct.

Q128. IUPAC name of this is (CH3)2 - CH - CH (C2H5) - C(CH3)3 :

• A. 3-ethyl-2,2,4-trimethylpentane✓
• B. 4-ethyl-2,2,4-trimethylpentane
• C. 5-ethyl-2,2,4-trimethylpentane
• D. 2-ethyl-2,2,4-trimethylpentane
• E. 1-ethyl-2,2,4-trimethylpentane

Explanation: The IUPAC name for the given compound (CH3)2-CH-CH(C2H5)-C(CH3)3 is "3-ethyl-2,2,4-trimethylpentane." Here's how the name is derived:1. Identify the longest continuous carbon chain, which in this case is a five-carbon chain.2. Number the carbon chain to give the substituents the lowest possible locants. In this case, we start numbering from the end nearest to the ethyl group, so the ethyl group is located on carbon 3.3. Assign substituent names and locants. The methyl groups attached to carbon 2 and carbon 4 are called "2,2-dimethyl" and "2,4-dimethyl," respectively. The ethyl group attached to carbon 3 is named "ethyl."4. Combine all the parts to form the complete IUPAC name: "3-ethyl-2,2,4-trimethylpentane."Therefore, the compound (CH3)2-CH-CH(C2H5)-C(CH3)3 is named 3-ethyl-2,2,4-trimethylpentane.

Q129. Which of the following carboxylic acids will be the most acidic?

• A. CH3CHClCH2COOH
• B. CH3CH2CCl2COOH✓
• C. CH3CH2CHClCOOH
• D. CH3CH2CH2COOH

Explanation: The acidity of carboxylic acids increases with the presence of electron-withdrawing groups (like-CI) near the -COOH group. CH3CH2CCI2COOH has two chlorine atoms on the B-carbon, which strongly stabilize the carboxylate ion through the inductive effect. Fewer or more distant chlorines (as in the other options) make the acid less acidic.

Q130. Which of the following cannot be used to convert butanoic acid to butanoyl chloride?

• A. PCl3
• B. PCl5
• C. CCl4✓
• D. SOCl2

Explanation: PCl3, PCl5, and SOCl2 can be used to add Cl atoms in place of the OH group. CCl4 is a carbon tetrachloride that cannot be used for this purpose.

Q131. Phenylmethyl ketone can be converted into ethyl benzene in one step by using:

• A. LiAlH4
• B. Zn(Hg)-HCl✓
• C. NaBH4
• D. CH3MgI

Explanation: The reaction is Clemmensen reduction. The reaction of aldehydes and ketones with zinc amalgam (Zn/Hg alloy) in concentrated hydrochloric acid, which reduces the aldehyde or ketone to a hydrocarbon, is called Clemmensen reduction.

Q132. The oxidation state of “S’ in the (S2O3)-2 is:

• A. +4
• B. +6
• C. -2
• D. +2✓

Explanation: Let the Oxidation number of Sulphur in S2O32- be x. Thus;2x+(-2 x 3)= -2 2x - 6= -2 2x= -2+6 2x=4 x=4\2 x=2 So, the oxidation state of sulphur is +2

Q133. The common oxidation number of halogens is:

• A. -1✓
• B. +1
• C. -2
• D. 0

Explanation: The most common oxidation state of halogens is -1. Halogens are the most electronegative elements of the periodic table. Their outer electron configuration is ns2, np5. If chlorine, for example, gains one more electron, the outer p orbitals are filled (resulting in a full octet). Since halogens are electronegative, they can easily remove an electron from nearby atoms to add to their valence p orbital achieving a full octet.

Q134. Which of the following will not undergo aldol condensation?

• A. Acetaldehyde
• B. Propanaldehyde
• C. Formaldehyde✓
• D. Trideuteroacetaldehyde

Explanation: The aldehydes that have alpha hydrogen atoms undergo aldol condensation reaction

Q135. Power developed by a person on eating 100g of ice per minute is (Latent heat of ice is 80 cal/g):

• A. 130 W
• B. 560 cal/sec
• C. 560 J/sec✓
• D. None of these

Explanation: A mass of ice eaten by the man per second.m =100/60=5/3 g/sLatent heat of ice,L = 80 cal/g.Therefore, energy required per second by the man in eating the ice, i.e., power developed by the man.= mL =5/3 x 80 cal/s 3=5x80/3x4.2J/s=560W

Q136. A block hangs freely from the end of a spring. A boy then slowly pushes the block upwards so that the spring becomes strain free. The gain in gravitational potential energy of the block during this process is equal to:

• A. Work done by the boy against the gravitational force acting on the block
• B. Loss of energy stored in the spring minus the work done by the tension in the spring
• C. Work done on the block by the boy plus the loss of energy stored in the spring✓
• D. Work done on the block by the boy minus the work done by the tension in the spring

Explanation: Let xo be the initial extension of the spring. Then the initial energy stored in the spring is: ½kxo2The gain in gravitational potential energy: mgh = mgxoThe work done increases the gravitational potential energy and decreases the spring’s potential energy. The total energy gained = gain in the gravitational potential energy - loss in spring’s potential energy. Therefore, work done by the boy (wb) = gain in the gravitational potential energy - loss in spring’s potential From here you can see that the gain in the gravitational potential energy of the block = work done by the boy + loss in the spring’s potential energy. Therefore, option C is the correct one.

Q137. If we are standing in a bus and the driver applies a brake then we feel:

• A. A pseudo force pushes backwards
• B. A pseudo force pushes forwards✓
• C. A real force pushes backwards
• D. A real force pushes forwards

Explanation: When a bus decelerates, passengers inside feel like they are being pushed forward due to inertia. This is because their bodies continue in motion at the original speed due to Newton's first law of motion, which states that an object in motion stays in motion unless acted upon by a net external force. In this scenario, a pseudo force acts forwards in the non-inertial reference frame of the bus. This is why Option B is correct. Option A is incorrect because the sensation is not backward. Option C is incorrect because the sensation of being pushed backward is not caused by a real force. Option D is incorrect because while you do feel a forward motion, it is not due to a real force acting on you, but rather your body's inertia.

Q138. The slope of displacement-time graph has the unit:

• A. m
• B. s
• C. m/s²
• D. m/s✓

Explanation: The slope of a displacement-time graph is given by:Δy/Δx = Δs/Δt, which is equal to velocity. Hence, the correct answer is m/s.Provided below, is an example where Δs, i.e. change in displacement, is given as 17.5 m, and Δt, i.e. change in time, is given as 5 seconds. The above formula is applied to find velocity, by finding the value of the slope.

Q139. On a planet, a vertically-launched projectile takes 12.5 s to return to its starting position. The projectile gains a maximum height of 170 m. The planet does not have an atmosphere. What is the acceleration of free fall on this planet?

• A. 2.2 m s−2
• B. 8.7 m s−2✓
• C. 27 m s−2
• D. 54 m s−2

Explanation: Explanation is given below:

Q140. If a wave can be polarized, it means, it is:

• A. Longitudinal wave
• B. Stationary wave
• C. Superimposed wave
• D. Transverse wave✓

Explanation: Only transverse waves can be polarised. Longitudinal waves cannot be polarised.Transverse: vibrations perpendicular to the direction of travel of the wave.Longitudinal: vibrations parallel to the direction of travel of the wave.Sound waves are longitudinal so they cannot be polarised.Polarised: the wave vibrations occur in one plane onlyUnpolarised: the wave vibrations occur in all planes perpendicular to the direction of travel.The reason that only transverse waves can be polarised is that their vibrations can potentially occur in all directions perpendicular to the direction of travel. It is therefore possible to confine the vibrations to a single plane. Or put another way an unpolarised transverse wave is a 3D shape, it is therefore possible to confine it to a 2D shape (a plane). The vibrations of a longitudinal wave occur along a single line, it is therefore not possible to confine that to a plane, i.e. a 1D shape cannot be confined within a 2D shape. Similarly, Stationary waves and superimposed waves can not be polarised as they are along a single line.VIDEO EXPLANATION

Q141. If the body is rotating with uniform angular velocity, then its torque is:

• A. Zero✓
• B. 90
• C. 1
• D. -1

Explanation: Torque will be zero because the force on the object is zero, since it is not accelerating. And also if the body is at rest or rotating with uniform angular velocity the angular acceleration will be zero in this case the torque acting on a body will be zero.Torque is given by solution i.e. torque = r.F sin (theta)Here force = maAcceleration is given by change in velocity/timeIf the change in velocity is zero, acceleration is zero, force is zero, thus torque is also zero. Any other value is not remotely possible

Q142. The angular velocity of the minute hand of a clock is:

• A. 2π/60 rads-1
• B. π/24 rads-1
• C. 2π/3600 rads-1✓
• D. π/3600 rads-1

Explanation: The minute hand of a clock completes a full revolution (2π radians) in one hour, which is 3600 seconds. Therefore, the angular velocity is calculated using the formula:Angular velocity (ω) = θ/twhere θ is the angle of rotation in radians, and t is the time in seconds. Plugging in the values, we have:ω = 2π/3600 rads-1This makes Option C the correct choice.Options A and B incorrectly calculate the time or angle for one full rotation. Option D incorrectly assumes the angle for a full rotation is π radians instead of 2π radians.

Q143. When a body is whirled in a horizontal circle by means of a string, the centripetal force is supplied by:

• A. Mass of a body
• B. Tension in the string✓
• C. Velocity of a body
• D. Centripetal acceleration

Explanation: Option B is correct. Yes, the centripetal force is supplied by the tension in the string. When a body is whirled in a horizontal circle by means of a string, the string exerts a force on the body towards the centre of the circle. This force is called the centripetal force. The centripetal force is necessary to keep the body moving in a circular path. The tension in the string is the force that the string exerts on the body. The tension in the string is equal to the centripetal force. The tension in the string is given by the following equation:T = Fc = mv2/r

Q144. The body of a car is supported by four springs each of constant 2000 Nm-1. What will be the value of spring constant for this combination of springs?

• A. 2000 Nm-1
• B. 600 Nm-1
• C. 8000 Nm-1✓
• D. 4000 Nm-1

Explanation: When multiple springs are connected in parallel, the overall spring constant (ktotal) is the sum of the individual spring constants. In this case, each spring has a constant of 2000 Nm-1. Therefore, for four identical springs in parallel, the effective spring constant is 4 × 2000 Nm-1 = 8000 Nm-1, making Option C correct. Option A is incorrect because it represents the spring constant of a single spring. Option B incorrectly assumes a series arrangement, and Option D fails to account for all four springs.

Q145. The oscillating object overshoots the rest position due to:

• A. Restoring force
• B. Inertia✓
• C. Gravitational potential energy
• D. Elastic potential energy

Explanation: To get oscillations, a body is pulled away from its resting or equilibrium position and then released. The body oscillates due to a restoring force. Under the action of this restoring force, the body accelerates and overshoots the rest position due to inertia.

Q146. When an ideal gas of constant mass is heated in a container of fixed volume, what is the reason for the increase in pressure of the gas?

• A. The number of molecules per unit volume increases
• B. The molecules occupy greater volume of the container
• C. The average force per impact at the container wall increases✓
• D. The molecules collide with each other with greater force

Explanation: The number of molecules per unit volume cannot increase because as specified by the question statement, the mass is constant. Moreover, molecules can only occupy the volume of the container. Since the volume of the container is fixed, they can't occupy a greater volume. Molecules do collide with each other with greater force but that is not the reason for the increase in the pressure of the gas. Molecules of gases are contiually colliding with each other and with the walls of the container. When a molecule collides with the wall, it exerts a small force on the wall. The pressure exerted by the gas is due to the sum of all these collision forces with the wall. As heat is supplied, molecules gain greater Kinetic Energy and collide with the wall harder and faster.

Q147. The angular measurement is known as _ measurement.

• A. Parameter
• B. Area
• C. Circumference✓
• D. All of these

Explanation: The correct answer is 'Circumference' because angular displacement (θ) is calculated as the arc length (S) divided by the radius (r) of the circle, expressed in the formula θ = S/r. This shows that angular measurement is directly related to the arc length, which is a segment of the circumference. The other options, 'Parameter' and 'Area', do not pertain to this specific calculation as they refer to different concepts and do not describe the relationship between angular displacement and circular measurements.

Q148. Acceleration in the simple pendulum is always _ to displacement.

• A. Inversely proportional
• B. Directly proportional✓
• C. Acting positive
• D. Independent

Explanation: Option B is correct because in a simple pendulum, the acceleration is directly proportional to the displacement from the equilibrium position. According to Hooke's law, the restoring force (and hence acceleration) is directly proportional to the displacement. This relationship holds as long as the angles are small, and the pendulum follows simple harmonic motion.

Q149. Velocity of sound in air is 332m/s. Velocity of sound in vacuum would be:

• A. More than 332m/s
• B. Less than 332m/s.
• C. 332m/s
• D. Zero✓

Explanation: Sound waves are longitudinal waves and they need a medium to travel. Thus, they cannot travel in vaccum.

Q150. The diagram shows a wire, carrying a current 'I', placed between the poles of a magnet. In which direction does the force on the wire act?

• A. Upwards
• B. Downwards✓
• C. Towards the ‘N’ pole of the magnet
• D. Towards the ‘S’ pole of the magnet

Explanation: We can determine the direction of the force on the current-carrying wire using Fleming's Left-Hand Rule.Step-by-step explanation:Magnetic field direction (B):It is from the North (N) pole to the South (S) pole (left to right).Current direction (I):The current is going upwards (as shown by the arrow labeled I).Force direction (F):By Fleming's Left-Hand Rule:First finger = Magnetic field (left to right),Second finger = Current (upwards),Thumb = Force (direction of motion).When you align your left hand as per this rule, the thumb points out of the page (towards you).

Q151. The ratio of the number of turns in primary and secondary coils of a transformer is 1:20. The ratio of the currents in the primary and secondary will be

• A. 1:20
• B. 20:1✓
• C. 1:400
• D. 400:1

Explanation: Explanation is giving below:

Q152. The change in resistance of metallic conductor at temperature below 0 degrees is:

• A. Non-linear
• B. Curve
• C. Linear✓
• D. Curvilinear

Explanation: The resistance increases as the temperature of metallic conductor increase with increase in temperature.Thee graph between resistance and temperature is linear for both increasing and decreasing.

Q153. Some ice, at its melting point, is added to m kg of water at the initial temperature of 290K. The ice melts completely and the final temperature of the water is 273K. If c is the specific heat capacity of the water and L is the latent heat of fusion of ice, what is the minimum mass of ice that is required?

• A. 17mc/L✓
• B. L/17mc
• C. 17m/Lc
• D. 290m/Lc

Explanation: Refer to the working below:

Q154. The force between two charges Q and q, separated by a distance is F. What will be the force between them when the distance between them is d/2?

• A. 4 F✓
• B. 2 F
• C. F
• D. F/2

Explanation: According to Coulomb's law of electrostatic force, the force between the two charges is directly proportional to the product of the charges and inversely proportional to the square of the distance between them. F = k q1q2/d²Where k is constant, q1 and q2 are two point charges and d the distance between them. If the distance between the charges is d/2 and there is no change in chargesThe new force becomesF’=kq1q2/(d/2)²F’=k q1q2/(d²/4)F’=4FWhich means, force will be 4 times of the initial value.

Q155. What is the relationship between Power, Current and voltage?

• A. P=V/I
• B. P=VI✓
• C. 2P=I+V
• D. All of them

Explanation: Correct option is B.Electrical power is the product of voltage and current. P = V X IP = E t.P = W t.P = V 2 /R.P=I2R

Q156. Object A has a charge of 15 mC, and object B has a charge of 10 mC. Which statement is true about the electric forces on the objects?

• A. FAB = -3 FBA
• B. FAB = - FBA✓
• C. 3 FAB = - FBA
• D. -3 FAB = 2 FBA

Explanation: Option B is correct option.

Q157. Magnetic force on a charged particle is:

• A. QvBl
• B. None of these
• C. QvB cosθ
• D. QvB sinθ✓

Explanation: When a charge moves through a magnetic field, a force is applied on it which is given by:F = QvB sinθQvBl is the motional EMF produced when a conductor moves through a static magnetic field.

Q158. In a full-wave bridge rectification, the number of diodes used are:

• A. 1
• B. 2
• C. 3
• D. 4✓

Explanation: The full-wave rectifier circuit consists of 4 diodes arranged in a tetrahedral connection. When we have the upper side of the AC supply as positive, the current flows through D1 to the load and returns through D2 at the temporary negative terminal of the AC supply. When the bottom side of the AC supply is positive, due to the constant change in polarity, the current, conventionally, flows through D3 to the load and returns to the supply by passing through D4. It reaches the supply at the now negative terminal of the AC supply which is the upper side of the supply.

Q159. An alternating voltage V (in volts) is represented by the equation:V = 300 sin(100πt) What is the value of “f” for this voltage?

• A. 100 Hz
• B. 50 Hz✓
• C. 25 H
• D. 200 Hz

Explanation: Voltage = Maximum Voltage x sin (2πft)Therefore, 2f = 100 and frequency = 50 Hz

Q160. The use of a capacitor filter in a rectifier circuit gives satisfactory performance only when the load:

• A. The current is high
• B. The current is low✓
• C. Voltage is high
• D. The voltage is low

Explanation: A capacitor filter in a rectifier circuit is used to smooth out the output voltage and reduce the ripple factor.Only when load resistance is large, discharge time is large, and the current passing through it is low

Q161. Which one of the following is not electromagnetic in nature?

• A. X-rays
• B. Gamma rays
• C. Cathode rays✓
• D. Infrared rays

Explanation: Cathode rays EM waves travel with a constant velocity of 3.00x10⁸ ms-1 in vacuum. They are deflected neither by the electric field, nor by the magnetic field. These waves do not require a medium to travel from one place to another. As cathode rays negate all these properties, they are not considered as EM waves.

Q162. The waves which can travel directly along surface of the earth are known as

• A. Ground waves✓
• B. X-ray
• C. α − rays
• D. Sky waves

Explanation: The waves which can travel directly along surface of the earth are known as ground waves. The ground wave is the preferred propagation type for long distance communication using frequencies below 3 MHz (the earth behaves as a conductor for all frequencies below 5 MHz). The ground wave is also used for short distance communications using frequencies between 3 and 30 MHz.

Q163. A TV tower has a height of 100m. The average population density around the tower is 1000 per km2 . The radius of the earth is 6.4x106 m. × The population covered by the tower is

• A. 2x106
• B. 3x106
• C. 4x106✓
• D. 6x106

Explanation: d = √(2Rh)where:• d = maximum distance covered by the tower• R = radius of the Earth = 6.4 * 10 ^ 6 m• h = height of the tower = 100mStep 1: Calculate the Coverage Radiusd = √(2(6.4 ×10 ^ 6) × 100) d = √{1.2×10^9}]A = πd ^ 2A = 3.14 × (35.8) ^ 2A = 3.14 × 1280A = 4020 km ^ 2Given that the population density is 1000 people per km², the total population covered is:Population = Area × Density4020 × 1000= 4.02 × 10^6

Q164. The valence band and conduction band of a solid overlap at low temperature, the solid may be:

• A. A metal✓
• B. A semiconductor
• C. An insulator
• D. None of these

Explanation: In the band theory of solids, conductors like metals are characterized by an overlap between the valence band and the conduction band. This overlap enables electrons to move freely, allowing metals to conduct electricity at low temperatures without requiring additional energy to excite electrons. In contrast, semiconductors have a small band gap with no overlap, and insulators have a large band gap, preventing electron movement between the bands. Therefore, the correct answer is that the solid is a metal.

Q165. Assertion: In n-type semiconductors electrons are the majority charge carriers and holes are the minority charge carriers.Reason: n-type semiconductor is electrically neutral.

• A. If both Assertion & Reason are true and the reason is the correct explanation of the assertion
• B. If both Assertion & Reason are true but the reason is not the correct explanation of the assertion✓
• C. If Assertion is a true statement but Reason is false
• D. If both Assertion and Reason are false statements

Explanation: The assertion is true: In n-type semiconductors, electrons are the majority charge carriers and holes are the minority charge carriers. This is due to the doping process that adds extra electrons to the semiconductor material. The reason is also true: n-type semiconductors are electrically neutral because the number of positive charges (protons in the nucleus) balances the number of negative charges (electrons). However, the reason does not explain why electrons are the majority carriers; it is an independent fact about the semiconductor's electrical neutrality. Hence, Option B is the correct answer. Options A, C, and D are incorrect because they misrepresent the truth value or the explanatory power of the reason in relation to the assertion.

Q166. Platinum wire becomes yellow at a temperature of _ degree C.

• A. 900
• B. 500
• C. 1300✓
• D. 1600

Explanation: If black wire of platinum is heated its colour first appears red, then yellow and finally white. This can be explained by wein’s displacement law. At low temperatures (500 degree celsius) the wire emits electromagnetic radiations of longer wavelengths so it appears dull red. As the temperature increases the wavelength emitted shortens and the colour changes from red to orange (1100 degree celsius) to yellow (1300 degree celsius) and ultimately white(1600 degree celsius) when radiations of all wavelengths are being emitted. PMC PAPER 23 2021 150-210

Q167. The electron is purely a _ when free.

• A. Particle nature
• B. Wave nature
• C. Dual nature✓
• D. It transforms into a photon

Explanation: According to the principles of quantum mechanics, electrons (and other particles) exhibit both wave-like and particle-like behavior. This duality is known as wave-particle duality. When not confined, electrons can exhibit wave-like behavior in certain experiments, such as in electron diffraction patterns. At the same time, they can behave as discrete particles with well-defined positions and momenta.

Q168. Work function was given by:

• A. Newton
• B. Heisenberg
• C. Einstein✓
• D. Bohr

Explanation: Work function is the minimum energy required to cause the photoelectric effect. It is constant for a particular material. Absorption of energy equal to the work function causes electrons to be excited enough to come up to the surface of the material. Surplus energy will cause the emission of the electron from the surface. This can be explained from the Photoelectric Effect equation discovered by Einstein: KEmax = hfo + hf (where KEmax is the energy of the incident photon, hfo is the work function, hf is the KE of the electron)

Q169. In Davisson-Germer experiment, the diffracted electron beam from crystal shows:

• A. Particle property
• B. Light property
• C. Wave property✓
• D. Quantum property

Explanation: Diffracted electron beam from crystal shows wave nature. Davisson Germer experiment showed that electron beams can undergo diffraction when passed through atomic crystals. This shows the wave nature of electrons as waves can exhibit interference and diffraction.

Q170. A set of atoms in an excited state decays:

• A. In any general state with lower energy✓
• B. In any state when excited by electric field
• C. In any state when excited by magnetic field
• D. None of these options are correct

Explanation: As we know, atoms are stable in the ground state, when they move to another level by gaining energy, they get excited and are ready to lose energy to get back to the ground state. This shows, generally excited state atoms decay to any of the states with lower energy.Hence,the correct option is A in any general state with lower energy which is more stable than the excited state.

Q171. Complete the sequence:2, 15, 41, 80, _

• A. 111
• B. 120
• C. 121
• D. 132✓

Explanation: Find the differences between consecutive terms:15 - 2 = 1341 - 15 = 2680 - 41 = 39Notice the pattern in the differences: The differences are increasing by 13 each time (13, 26, 39).Find the next difference: The next difference would be 39 + 13 = 52.Find the next term in the sequence: Add the next difference to the last term: 80 + 52 = 132.Therefore, the next number in the sequence is 132.

Q172. 8, 10, 14, 18, _ , 34, 50 , 66:

• A. 24
• B. 25
• C. 26✓
• D. 27

Explanation: The series progresses as follows: starting from 8, we add 2 to get 10, then add 4 to get 14, again add 4 to get 18. The next step requires adding 8 to 18, resulting in 26. This fits the established pattern of increasing increments: +2, +4, +4, +8. The subsequent number in the series is then 34, followed by 50, and 66, which confirm the sequence's consistency. Options A, B, and D are incorrect as they do not adhere to this increment pattern.

Q173. Statements: 1. Blueberries cost more than strawberries. 2. Blueberries cost less than raspberries. 3. Raspberries cost more than strawberries and blueberries. If the first two statements are true, the third statement is:

• A. True✓
• B. False
• C. Uncertain
• D. None of these

Explanation: From the first two statements, we can establish the cost order: Raspberries > Blueberries > Strawberries. This directly confirms that raspberries cost more than both of the other fruits, making the third statement true.

Q174. The Emporium Mall has more stores than the Pakages Mall.The Amanah Mall has fewer stores than the Pakages Mall.The Emporium Mall has more stores than the Amanah Mall.If the first two statements are true, the third statement is

• A. True✓
• B. FALSE
• C. Uncertain
• D. None of these

Explanation: ExplanationFrom the first two statements, you know that the Emporium mall has the most stores, so the Emporium Mall would have more stores than the packages Mall.

Q175. l.The car manufacturing companies have recently increased the prices of mid-sized cars. ll. The Government recently increased the duty on mid-sized cars.

• A. Statement I is the cause and statement II is its effect.
• B. Both the statements I and II are effects of some common cause.
• C. Both the statements I and II are independent causes.
• D. Statement II is the cause and statement I is its effect.✓

Explanation: In this logical reasoning question, we are examining the cause and effect relationship between the two statements. Statement II states that the government has increased the duty on mid-sized cars, which would logically increase production costs for car manufacturers. In response to this increased cost, car manufacturers would raise the prices of mid-sized cars, as indicated in Statement I.Therefore, Statement II (government increased duty) is the cause, and Statement I (car manufacturers increased prices) is the effect.Other options are incorrect because they either suggest that the price increase caused the duty increase, both are effects of a common cause, or both occurred independently, none of which align with the logical progression from cause to effect in the given statements.

Q176. An autograph can not exist without?

• A. Actor
• B. Singer
• C. Player
• D. Pen✓

Explanation: An autograph is defined as a person's handwritten signature, mostly of someone famous among the masses.As a pen is necessary to do a signature by hand, hence it is the answer.

Q177. Pick the odd word out:

• A. Just
• B. Fair
• C. Equitable
• D. Biased✓

Explanation: The words "just," "fair," and "equitable" are all synonyms related to impartiality and justice. "Biased" is an antonym, meaning to show prejudice for or against something, making it the odd one out.

Q178. Statements: 1. Tanya is older than Eric. 2. Cliff is older than Tanya. 3. Eric is older than Cliff. If the first two statements are true, the third statement is:

• A. True
• B. False✓
• C. Uncertain
• D. None of these

Explanation: If Cliff is older than Tanya, and Tanya is older than Eric, then the age order is Cliff > Tanya > Eric. Therefore, the statement "Eric is older than Cliff" must be false.

Q179. Each problem consists of three statements. Based on the first two statements, the third statement may be true, false, or uncertain.Blueberries cost more than strawberries.Blueberries cost less than raspberries.Raspberries cost more than both strawberries and blueberries.If the first two statements are true, the third statement is:

• A. True✓
• B. False
• C. Uncertain
• D. None of these
• E. None of these

Explanation: The first two statements provide a clear hierarchy of fruit prices: blueberries are more expensive than strawberries, and raspberries are more expensive than blueberries. Therefore, raspberries must be more expensive than both strawberries and blueberries, making the third statement true. Option A is correct as it accurately reflects this deduction. Options B and C are incorrect because the cost relationships provided lead to a definite conclusion about the third statement. Option D is also incorrect as it suggests there is no correct option, which contradicts the evidence given.