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150 questions
  1. BiologyBreathing and Exchange of Gases·Respiratory organs — human respiratory systemEasy
    Q1.Which one of the following correctly gives the sequence of passages through which inhaled air travels, from the external nostrils to the alveoli, in humans?
    1. (A)External nostrils → larynx → pharynx → trachea → bronchioles → primary bronchi → alveoli
    2. (B)External nostrils → pharynx → trachea → larynx → primary bronchi → bronchioles → alveoli
    3. (C)External nostrils → pharynx → larynx → trachea → primary bronchi → bronchioles → alveoli
    4. (D)External nostrils → larynx → trachea → pharynx → bronchioles → alveoli
  2. BiologyBreathing and Exchange of Gases·Respiratory organs — larynxEasy
    Q2.The larynx, commonly called the sound box, lies between the pharynx and the trachea. Which of the following correctly describes a key feature of the larynx and its role during swallowing?
    1. (A)It lies below the diaphragm and its main job is to trap dust particles in mucus
    2. (B)It is the widest part of the respiratory tract, positioned between the two bronchi, with no role during swallowing
    3. (C)It is a cartilaginous box that helps in sound production, and during swallowing its opening (the glottis) can be covered by a thin, elastic cartilaginous flap, the epiglottis, to prevent food from entering the larynx
    4. (D)It is a spongy, elastic organ made of bronchioles and alveoli where gas exchange occurs
  3. BiologyBreathing and Exchange of Gases·Mechanism of breathingMedium
    Q3.During a normal, quiet inspiration in humans, contraction of the diaphragm and the external intercostal muscles brings about a pressure change that draws air into the lungs. Which of the following correctly explains this sequence of events?
    1. (A)The diaphragm relaxes and arches upward while the external intercostals contract, decreasing thoracic volume and pressure, which draws air in
    2. (B)Both the diaphragm and the intercostal muscles contract to decrease thoracic volume, increasing intra-pulmonary pressure and pushing air out
    3. (C)The diaphragm contracts and flattens while the external intercostals lift the ribs and sternum outward, increasing thoracic volume; intra-pulmonary pressure falls below atmospheric pressure, so air flows in
    4. (D)Air enters the lungs because the alveoli actively pump air in using ciliary movement, independent of thoracic volume changes
  4. BiologyBreathing and Exchange of Gases·Respiratory volumes and capacitiesMedium
    Q4.For an adult, take Tidal Volume (TV) = 500 mL, Inspiratory Reserve Volume (IRV) = 2500 mL and Expiratory Reserve Volume (ERV) = 1000 mL, values within the approximate ranges NCERT gives for a healthy adult. What is the Vital Capacity?
    1. (A)2500 mL
    2. (B)3500 mL
    3. (C)4000 mL
    4. (D)5000 mL
  5. BiologyBreathing and Exchange of Gases·Exchange of gasesMedium
    Q5.Efficient gas exchange at the alveoli depends on the properties of the gases themselves as well as on the structure of the membrane they must cross. Evaluate the two statements below on this exchange.
    • Statement I: The solubility of CO₂ is 20–25 times higher than that of O₂, so the amount of CO₂ that can diffuse through the diffusion membrane per unit difference in partial pressure is much higher than that of O₂.
    • Statement II: The diffusion membrane is made up of three major layers — the thin squamous epithelium of the alveoli, the endothelium of the alveolar capillaries, and the basement substance in between them — and its total thickness is much less than a millimetre.
    1. (A)Both Statement I and Statement II are correct
    2. (B)Statement I is correct, but Statement II is incorrect
    3. (C)Statement I is incorrect, but Statement II is correct
    4. (D)Both Statement I and Statement II are incorrect
  6. BiologyBreathing and Exchange of Gases·Transport of gases — oxygenMedium
    Q6.Read the following two statements about the transport of oxygen in human blood and choose the option that correctly evaluates them.
    • Statement I: About 97% of the oxygen carried in blood is bound to haemoglobin as oxyhaemoglobin, and each haemoglobin molecule can bind a maximum of four O₂ molecules.
    • Statement II: A higher partial pressure of CO₂, a higher hydrogen ion concentration, and a higher temperature, as found in the tissues, all favour dissociation of oxygen from oxyhaemoglobin, helping O₂ unload where it is needed.
    1. (A)Both Statement I and Statement II are correct
    2. (B)Statement I is correct, but Statement II is incorrect
    3. (C)Statement I is incorrect, but Statement II is correct
    4. (D)Both Statement I and Statement II are incorrect
  7. BiologyBreathing and Exchange of Gases·Transport of gases — carbon dioxideHard
    Q7.Only a small fraction of the CO₂ produced by tissues travels dissolved in plasma. Which of the following correctly describes how most CO₂ is carried in the blood, and which enzyme catalyses the key step of this route?
    1. (A)About 70% of CO₂ is carried as carbamino-haemoglobin, formed by CO₂ binding directly to the haem group of haemoglobin, a reaction catalysed by carbonic anhydrase
    2. (B)Nearly all CO₂ diffuses freely and travels dissolved in plasma, since CO₂, unlike O₂, needs no carrier
    3. (C)About 70% of CO₂ is transported as bicarbonate ions, formed after CO₂ combines with water inside RBCs to give carbonic acid, which dissociates into H⁺ and HCO₃⁻; carbonic anhydrase, abundant in RBCs, catalyses the CO₂ + H₂O step
    4. (D)About 70% of CO₂ combines irreversibly with plasma proteins to form stable carbaminohaemoglobin, catalysed by RuBisCO present in RBCs
  8. BiologyBreathing and Exchange of Gases·Regulation of respirationHard
    Q8.Breathing rate is adjusted moment to moment by chemical signals reaching the medulla, not by mechanical stretch alone. Evaluate the following Assertion and Reason on how CO₂ levels drive this regulation.
    • Assertion (A): A rise in the CO₂ concentration of blood changes the rate and depth of breathing far more strongly than a comparable fall in O₂ concentration.
    • Reason (R): A chemosensitive area adjacent to the rhythm centre in the medulla, together with receptors associated with the aortic arch and carotid artery, is highly sensitive to CO₂ and H⁺ concentration and signals the rhythm centre to make the necessary adjustments.
    1. (A)Both A and R are true, and R is the correct explanation of A
    2. (B)Both A and R are true, but R is not the correct explanation of A
    3. (C)A is true, but R is false
    4. (D)A is false, but R is true
  9. BiologyBreathing and Exchange of Gases·Disorders of the respiratory systemEasy
    Q9.Emphysema is a chronic respiratory disorder commonly caused by long-term cigarette smoking. Which of the following correctly describes what happens to the lungs in this disease and its immediate functional consequence?
    1. (A)The bronchi and bronchioles become inflamed, causing difficulty in breathing with wheezing
    2. (B)Fine dust particles accumulate in the lungs and stimulate fibrous tissue growth, reducing lung flexibility
    3. (C)The walls of the alveoli are damaged and adjacent alveoli merge, decreasing the total surface area available for gas exchange
    4. (D)The alveolar surface area increases as new alveoli are formed to compensate for reduced oxygen availability
  10. BiologyBreathing and Exchange of Gases·Disorders of the respiratory systemMedium
    Q10.Workers in industries involving grinding or stone-breaking are exposed over years to excessive dust in their workplace. What kind of respiratory damage does chronic exposure of this sort typically cause, and what is this category of disorders called?
    1. (A)The dust particles are trapped entirely by nasal hair and mucus, so no lasting lung damage occurs even after years of exposure
    2. (B)The dust causes reversible bronchoconstriction that resolves fully within hours of leaving the workplace, similar to asthma
    3. (C)Chronic inhalation of fine dust particles causes inflammation leading to fibrosis of the lungs, reducing their functioning; such conditions are called occupational respiratory disorders
    4. (D)The dust particles are absorbed into the blood through the alveoli and cause damage mainly to the liver rather than the lungs
  11. BiologyCell: The Unit of Life·Cell TheoryEasy
    Q11.The cell theory, as it stands today, states that all living organisms are composed of cells and cell products, and that new cells arise only from pre-existing cells. Which scientist added this second part — that cells arise only from pre-existing cells — to Schleiden and Schwann's original formulation?
    1. (A)Robert Hooke
    2. (B)Rudolf Virchow
    3. (C)Antony van Leeuwenhoek
    4. (D)Robert Brown
  12. BiologyCell: The Unit of Life·RibosomesEasy
    Q12.A prokaryotic ribosome sediments as a 70S particle made of a 50S and a 30S subunit. Free ribosomes lying in the cytoplasm of a eukaryotic cell are larger. What is their sedimentation coefficient and subunit composition?
    1. (A)70S, made of a 50S and a 30S subunit
    2. (B)80S, made of a 60S and a 40S subunit
    3. (C)80S, made of a 50S and a 30S subunit
    4. (D)100S, made of a 70S and a 30S subunit
  13. BiologyCell: The Unit of Life·Plasma membraneMedium
    Q13.The fluid mosaic model of the plasma membrane, proposed by Singer and Nicolson in 1972, describes how membrane lipids and proteins are organised. Which statement correctly describes this arrangement?
    1. (A)The membrane is a rigid, static lipid bilayer, with all proteins fixed permanently on its outer surface only
    2. (B)Proteins form a continuous layer completely coating both surfaces of the lipid bilayer, like bread around a filling
    3. (C)The lipid bilayer is quasi-fluid, and most proteins are embedded to varying depths, giving the membrane a mosaic look; proteins and lipids can move laterally
    4. (D)The membrane is composed almost entirely of protein, with only a few scattered lipid molecules trapped between them
  14. BiologyCell: The Unit of Life·Endomembrane system — Golgi apparatusMedium
    Q14.The Golgi apparatus is an important part of the endomembrane system that packages materials received from the endoplasmic reticulum. Evaluate the two statements below on its structure.
    • Statement I: The Golgi apparatus consists of many flat, disc-shaped sacs called cisternae, which are stacked parallel to each other and concentrically arranged near the nucleus.
    • Statement II: The Golgi cisternae have a convex cis face, called the forming face, and a concave trans face, called the maturing face; the two faces are entirely different but interconnected.
    1. (A)Both Statement I and Statement II are correct
    2. (B)Statement I is correct, but Statement II is incorrect
    3. (C)Statement I is incorrect, but Statement II is correct
    4. (D)Both Statement I and Statement II are incorrect
  15. BiologyCell: The Unit of Life·MitochondriaMedium
    Q15.Mitochondria are unusual among cytoplasmic organelles in carrying a genome of their own, in addition to their distinctive double-membrane, cristae-folded architecture. Evaluate the two statements below on mitochondrial structure and genetics.
    • Statement I: Mitochondria are bound by a double membrane, and the inner membrane is thrown into infoldings called cristae that increase the surface area for ATP synthesis.
    • Statement II: The mitochondrial matrix contains single circular DNA, a few RNA molecules, ribosomes, and the enzymes required for the synthesis of some of the organelle's own proteins.
    1. (A)Both Statement I and Statement II are correct
    2. (B)Statement I is correct, but Statement II is incorrect
    3. (C)Statement I is incorrect, but Statement II is correct
    4. (D)Both Statement I and Statement II are incorrect
  16. BiologyCell: The Unit of Life·Endomembrane system — LysosomesMedium
    Q16.Lysosomes, popularly nicknamed the 'suicide bags' of the cell because of the powerful digestive enzymes they hold, belong to the endomembrane system. Which statement correctly describes how lysosomes are formed and what they contain?
    1. (A)They are formed by the packaging activity of the Golgi apparatus and contain hydrolytic enzymes that work best at an alkaline pH
    2. (B)They are bound by a membrane called the tonoplast and store cell sap that can occupy up to 90% of a plant cell's volume
    3. (C)They are formed by the packaging activity of the Golgi apparatus and are rich in hydrolytic enzymes (lipases, proteases, carbohydrases) that are optimally active at an acidic pH
    4. (D)They are membrane-less particles of RNA and protein that synthesise the digestive enzymes they carry
  17. BiologyCell: The Unit of Life·Mitochondria and plastidsHard
    Q17.Mitochondria and chloroplasts are unlike most other organelles in retaining a trace of genetic independence from the nucleus. Evaluate the following Assertion and Reason on why they are termed semi-autonomous.
    • Assertion (A): Mitochondria and plastids are described as semi-autonomous organelles.
    • Reason (R): Both organelles possess their own double-stranded circular DNA, 70S ribosomes, and the machinery to synthesise some of their own proteins, but still depend on nuclear genes for many other proteins.
    1. (A)Both A and R are true, and R is the correct explanation of A
    2. (B)Both A and R are true, but R is not the correct explanation of A
    3. (C)A is true, but R is false
    4. (D)A is false, but R is true
  18. BiologyCell: The Unit of Life·Cell wallMedium
    Q18.In a mature plant cell that has formed a secondary wall, the wall region between the cell and its neighbour shows three distinct layers. Which of the following correctly lists these layers from outermost to innermost?
    1. (A)Secondary wall (outermost) → primary wall → middle lamella (innermost)
    2. (B)Primary wall (outermost) → middle lamella → secondary wall (innermost)
    3. (C)Middle lamella (outermost) → primary wall → secondary wall (innermost)
    4. (D)Middle lamella (outermost) → secondary wall → primary wall (innermost)
  19. BiologyCell: The Unit of Life·Cilia and flagellaHard
    Q19.A transverse section through the shaft of a cilium or flagellum, viewed under the electron microscope, shows a characteristic microtubule arrangement called the axoneme. Which of the following correctly describes this arrangement and the structure that anchors it in the cell?
    1. (A)Nine central microtubules surrounded by two peripheral doublets, anchored by the nucleolus
    2. (B)Nine peripheral triplets and no central microtubules, anchored by a centrosome located inside the nucleus
    3. (C)Nine peripheral doublets of microtubules and one central pair (the '9 + 2' array), anchored at the base by a basal body structurally similar to a centriole
    4. (D)Nine peripheral doublets with no central microtubules, anchored directly to the Golgi apparatus
  20. BiologyCell: The Unit of Life·NucleusEasy
    Q20.Robert Brown first described the nucleus as a cell organelle in 1831. Inside the nucleoplasm, one or more dense, spherical structures are seen, and they are sites of active ribosomal RNA synthesis. What are these structures called, and are they bound by a membrane?
    1. (A)Nucleoid; bound by a single membrane
    2. (B)Nuclear envelope; bound by a double membrane
    3. (C)Nucleolus; not bound by any membrane
    4. (D)Chromatin network; bound by a single membrane
  21. ChemistryChemical Bonding and Molecular Structure·HybridisationEasy
    Q21.In ethyne (HC≡CH), what is the hybridisation of each carbon atom, and how many sigma (σ) bonds does each carbon form?
    1. (A)sp³; each carbon forms 4 σ bonds
    2. (B)sp²; each carbon forms 3 σ bonds
    3. (C)sp; each carbon forms 2 σ bonds
    4. (D)sp; each carbon forms 3 σ bonds
  22. ChemistryChemical Bonding and Molecular Structure·VSEPR theoryEasy
    Q22.Sulfur hexafluoride (SF₆) has 6 S–F bond pairs and no lone pair on the central sulfur atom. What molecular shape does VSEPR theory predict for it?
    1. (A)Trigonal bipyramidal
    2. (B)Square pyramidal
    3. (C)Octahedral
    4. (D)Square planar
  23. ChemistryChemical Bonding and Molecular Structure·Hydrogen bondingEasy
    Q23.Between hydrogen fluoride (HF) and hydrogen chloride (HCl), which molecule(s) show intermolecular hydrogen bonding?
    1. (A)Both HF and HCl show hydrogen bonding
    2. (B)Only HF shows hydrogen bonding
    3. (C)Only HCl shows hydrogen bonding
    4. (D)Neither HF nor HCl shows hydrogen bonding
  24. ChemistryChemical Bonding and Molecular Structure·Molecular orbital theory / bond orderMedium
    Q24.Using molecular orbital theory, what is the bond order of the nitrogen molecule (N₂), and is N₂ paramagnetic or diamagnetic?
    1. (A)Bond order 2; paramagnetic
    2. (B)Bond order 3; diamagnetic
    3. (C)Bond order 3; paramagnetic
    4. (D)Bond order 2.5; paramagnetic
  25. ChemistryChemical Bonding and Molecular Structure·Dipole momentMedium
    Q25.Boron trifluoride (BF₃) contains three polar B–F bonds, yet its measured net dipole moment is zero. What is the correct explanation?
    1. (A)The B–F bonds are actually non-polar because B and F have similar electronegativity
    2. (B)BF₃ is trigonal planar (sp² boron, 120° F–B–F angles), so the three equal bond dipoles cancel exactly by symmetry
    3. (C)The lone pair on boron cancels the bond dipoles
    4. (D)Fluorine's very high electronegativity prevents any dipole from forming in the first place
  26. ChemistryChemical Bonding and Molecular Structure·Hybridisation and VSEPR (expanded octet)Medium
    Q26.What is the hybridisation of sulfur and the molecular shape of SF₄?
    1. (A)sp³; tetrahedral
    2. (B)sp³d; see-saw shape (one equatorial lone pair)
    3. (C)sp³d; trigonal bipyramidal (no lone pair)
    4. (D)sp³d²; square pyramidal
  27. ChemistryChemical Bonding and Molecular Structure·Hybridisation and molecular shapeMedium
    Q27.The Assertion (A) and Reason (R) below concern the shape of a xenon fluoride. Read them and choose the option that correctly describes their relationship.
    • Assertion (A): Xenon tetrafluoride (XeF₄) has a square planar molecular shape.
    • Reason (R): The Xe atom in XeF₄ is sp³d² hybridised, and its two lone pairs occupy the axial positions of the octahedral electron-pair geometry, leaving the four F atoms and Xe in one plane.
    1. (A)Both A and R are true, and R is the correct explanation of A
    2. (B)Both A and R are true, but R is NOT the correct explanation of A
    3. (C)A is true, but R is false
    4. (D)A is false, but R is true
  28. ChemistryChemical Bonding and Molecular Structure·Molecular orbital theory / bond order trendsHard
    Q28.Two statements about the bond orders of O₂, O₂⁺ (dioxygenyl cation), and O₂⁻ (superoxide ion) are given below. Study them and choose the correct option.
    • Statement I: The bond order of O₂⁺ is higher than the bond order of O₂.
    • Statement II: The bond order of O₂⁻ is lower than the bond order of O₂.
    1. (A)Both Statement I and Statement II are correct
    2. (B)Statement I is correct, but Statement II is incorrect
    3. (C)Statement I is incorrect, but Statement II is correct
    4. (D)Both Statement I and Statement II are incorrect
  29. ChemistryChemical Bonding and Molecular Structure·VSEPR theory (expanded octet)Hard
    Q29.Chlorine trifluoride (ClF₃) has 3 Cl–F bond pairs and 2 lone pairs on the central chlorine atom. What molecular shape does VSEPR theory predict?
    1. (A)Trigonal planar
    2. (B)Trigonal bipyramidal
    3. (C)T-shaped
    4. (D)Bent (angular)
  30. ChemistryEquilibrium·Relationship between Kp and KcEasy
    Q30.For the gas-phase equilibrium 2SO₃(g) ⇌ 2SO₂(g) + O₂(g), which relation between Kp and Kc is correct?
    1. (A)Kp = Kc(RT)
    2. (B)Kp = Kc(RT)⁻¹
    3. (C)Kp = Kc(RT)³
    4. (D)Kp = Kc
  31. ChemistryEquilibrium·Factors affecting equilibria: Le Chatelier's principleEasy
    Q31.For the equilibrium N₂O₄(g) ⇌ 2NO₂(g), ΔH > 0, which change increases the amount of NO₂ present at the new equilibrium?
    1. (A)Compressing the mixture to a smaller volume at constant temperature
    2. (B)Adding a catalyst
    3. (C)Raising the temperature at constant pressure
    4. (D)Adding argon at constant volume
  32. ChemistryEquilibrium·Calculating equilibrium constantsMedium
    Q32.2.0 mol of A(g) and 2.0 mol of B(g) are placed in a sealed 2.0 L flask at a fixed temperature. The reaction A(g) + B(g) ⇌ 2C(g) reaches equilibrium when 1.6 mol of C is present. What is Kc?
    1. (A)2.22
    2. (B)16.0
    3. (C)0.563
    4. (D)1.78
  33. ChemistryEquilibrium·Ionization constants of weak acidsMedium
    Q33.What is the pH of a 0.020 M aqueous solution of a weak monobasic acid HA whose Ka = 2.0 × 10⁻⁵ at 298 K? (log 2 = 0.301, log 6.32 = 0.80)
    1. (A)1.70
    2. (B)3.20
    3. (C)6.40
    4. (D)4.70
  34. ChemistryEquilibrium·Common ion effect in ionization of acidsMedium
    Q34.Read the Assertion (A) and Reason (R) and choose the correct option.
    • Assertion (A): Dissolving solid sodium acetate in an aqueous solution of acetic acid raises the pH of the solution.
    • Reason (R): The added acetate ions shift the equilibrium CH₃COOH ⇌ CH₃COO⁻ + H⁺ to the left, lowering [H⁺].
    1. (A)Both A and R are true, and R is the correct explanation of A.
    2. (B)Both A and R are true, but R is not the correct explanation of A.
    3. (C)A is true, but R is false.
    4. (D)A is false, but R is true.
  35. ChemistryEquilibrium·Solubility product constantMedium
    Q35.A sparingly soluble salt M₂X dissociates as M₂X(s) ⇌ 2M⁺(aq) + X²⁻(aq). Its solubility product at 298 K is 3.2 × 10⁻¹¹. What is its molar solubility in pure water?
    1. (A)5.66 × 10⁻⁶ mol L⁻¹
    2. (B)3.17 × 10⁻⁴ mol L⁻¹
    3. (C)2.83 × 10⁻⁶ mol L⁻¹
    4. (D)2.0 × 10⁻⁴ mol L⁻¹
  36. ChemistryEquilibrium·The pH scale: strong basesEasy
    Q36.What is the pH of a 0.005 M aqueous solution of Ba(OH)₂ at 298 K? Assume complete dissociation. (Kw = 1.0 × 10⁻¹⁴, log 2 = 0.301)
    1. (A)11.70
    2. (B)2.30
    3. (C)2.00
    4. (D)12.00
  37. ChemistryEquilibrium·Buffer solutionsHard
    Q37.60 mL of 0.10 M aqueous NH₃ is mixed with 20 mL of 0.10 M HCl at 298 K. What is the pH of the resulting solution? (pKb of NH₃ = 4.75, log 2 = 0.301, log 3 = 0.477, Kw = 1.0 × 10⁻¹⁴)
    1. (A)8.95
    2. (B)9.55
    3. (C)4.45
    4. (D)9.73
  38. ChemistryEquilibrium·Relationship between equilibrium constant K and ΔG°Hard
    Q38.For a reaction at 300 K, ΔG° = +5.74 kJ mol⁻¹. What is the value of the equilibrium constant K at this temperature? (R = 8.314 J K⁻¹ mol⁻¹; e^(−2.30) ≈ 0.10)
    1. (A)10
    2. (B)5.0 × 10⁻³
    3. (C)0.998
    4. (D)0.10
  39. PhysicsLaws of Motion·ImpulseEasy
    Q39.A 0.40 kg football moving horizontally at 12 m/s strikes a vertical wall head-on and rebounds along the same line at 8 m/s. The ball is in contact with the wall for 0.05 s. What is the magnitude of the average force exerted by the wall on the ball?
    1. (A)32 N
    2. (B)96 N
    3. (C)160 N
    4. (D)8 N
  40. PhysicsLaws of Motion·Newton's second law of motionEasy
    Q40.A 5.0 kg block rests on a frictionless horizontal floor. It is pulled by a rope with a constant force of 20 N directed at 37° above the horizontal. The block stays in contact with the floor. Take sin 37° = 0.6 and cos 37° = 0.8. What is the acceleration of the block?
    1. (A)4.0 m s⁻²
    2. (B)3.2 m s⁻²
    3. (C)2.4 m s⁻²
    4. (D)0.32 m s⁻²
  41. PhysicsLaws of Motion·Newton's third law of motionEasy
    Q41.Four claims about action-reaction force pairs (Newton's third law) are listed below as I to IV. Select the option that names every correct claim and no incorrect one.
    • I. The action and reaction forces of a pair always act on two different bodies.
    • II. Action and reaction cancel each other, so the net force on any body is always zero.
    • III. For a book resting on a table, the book's weight and the normal force from the table on the book form an action-reaction pair.
    • IV. Action and reaction are equal in magnitude even when the interacting bodies are accelerating.
    1. (A)I and IV only
    2. (B)I, II and IV only
    3. (C)I, III and IV only
    4. (D)II and III only
  42. PhysicsLaws of Motion·Solving problems in mechanics (connected bodies)Medium
    Q42.Two blocks of masses 5 kg and 3 kg hang at the two ends of a light inextensible string that passes over a light frictionless pulley fixed to the ceiling. The system is released from rest. Take g = 10 m s⁻². What is the tension in the string while the blocks move?
    1. (A)30 N
    2. (B)37.5 N
    3. (C)40 N
    4. (D)50 N
  43. PhysicsLaws of Motion·FrictionMedium
    Q43.A 4 kg crate rests on a horizontal floor. The coefficient of static friction between the crate and the floor is 0.5 and the coefficient of kinetic friction is 0.4. A worker pushes the crate with a horizontal force of 18 N. Take g = 10 m s⁻². What is the frictional force acting on the crate?
    1. (A)20 N
    2. (B)18 N
    3. (C)16 N
    4. (D)2 N
  44. PhysicsLaws of Motion·Apparent weight (Newton's second law)Medium
    Q44.A 60 kg student stands on a bathroom scale placed on the floor of a lift. The lift is moving upward but slowing down at a steady rate of 2.5 m s⁻². Take g = 10 m s⁻². What force does the scale show?
    1. (A)750 N
    2. (B)600 N
    3. (C)450 N
    4. (D)150 N
  45. PhysicsLaws of Motion·Circular motion (car on a level road)Medium
    Q45.A car takes an unbanked, level circular turn of radius 50 m. The coefficient of static friction between the tyres and the road is 0.45. Take g = 10 m s⁻². What is the maximum speed at which the car can take the turn without skidding?
    1. (A)4.7 m/s
    2. (B)15 m/s
    3. (C)21.2 m/s
    4. (D)33.3 m/s
  46. PhysicsLaws of Motion·Solving problems in mechanics (friction with connected bodies)Hard
    Q46.A 4 kg block rests on a rough horizontal table. A light inextensible string tied to it runs horizontally to a light frictionless pulley at the table's edge and then hangs vertically, carrying a 2 kg block. The coefficient of kinetic friction between the 4 kg block and the table is 0.25. The system is released and the blocks slide. Take g = 10 m s⁻². What is the tension in the string?
    1. (A)10 N
    2. (B)13.3 N
    3. (C)16.7 N
    4. (D)20 N
  47. PhysicsLaws of Motion·Conservation of momentumHard
    Q47.A 60 kg skater stands at rest on frictionless ice holding a 3 kg ball. She throws the ball horizontally forward so that, just after release, the ball moves at 12 m/s relative to her. What is the skater's recoil speed relative to the ice?
    1. (A)0.57 m/s
    2. (B)0.60 m/s
    3. (C)0.63 m/s
    4. (D)11.4 m/s
  48. PhysicsMotion in a Straight Line·Average velocity and average speedEasy
    Q48.A cyclist rides 3.0 km due east along a straight road in 10 min, then turns around and rides 1.0 km due west along the same road in 5 min. For the whole 15-minute trip, what are the cyclist's average speed and the magnitude of the average velocity?
    1. (A)Average speed 16 km/h; average velocity 8 km/h
    2. (B)Average speed 8 km/h; average velocity 16 km/h
    3. (C)Average speed 16 km/h; average velocity 16 km/h
    4. (D)Average speed 15 km/h; average velocity 3 km/h
  49. PhysicsMotion in a Straight Line·Kinematic equations for uniformly accelerated motionEasy
    Q49.A car moving at 54 km/h on a straight level road brakes with constant deceleration and comes to rest after travelling 45 m. What is the magnitude of the deceleration?
    1. (A)32.4 m s⁻²
    2. (B)5.0 m s⁻²
    3. (C)2.5 m s⁻²
    4. (D)0.33 m s⁻²
  50. PhysicsMotion in a Straight Line·Position-time and velocity-time graphsEasy
    Q50.A student reviewing kinematics graphs for a body moving along a straight line writes four claims, labelled I to IV below. Identify which of the student's claims are physically correct.
    • I. The area under a velocity-time graph over an interval equals the displacement in that interval.
    • II. The slope of a position-time graph at an instant equals the acceleration at that instant.
    • III. A body can have zero velocity and a non-zero acceleration at the same instant.
    • IV. If the velocity and acceleration of a body have opposite signs, the body is speeding up.
    1. (A)I and III only
    2. (B)I, II and III only
    3. (C)II and IV only
    4. (D)I, III and IV only
  51. PhysicsMotion in a Straight Line·Free fallMedium
    Q51.A stone is released from rest at the top of a tower and falls freely to the ground. In the last one second of its fall it covers 35 m. Neglect air resistance and take g = 10 m s⁻². What is the height of the tower?
    1. (A)45 m
    2. (B)80 m
    3. (C)125 m
    4. (D)160 m
  52. PhysicsMotion in a Straight Line·Vertical motion under gravityMedium
    Q52.A ball is thrown vertically upward at 15 m/s from the edge of a cliff 20 m above flat ground. On the way down it just misses the cliff edge and lands on the ground at the foot of the cliff. Neglect air resistance and take g = 10 m s⁻². How long after the throw does the ball hit the ground?
    1. (A)1 s
    2. (B)2 s
    3. (C)3 s
    4. (D)4 s
  53. PhysicsMotion in a Straight Line·Uniform motion: position as a function of timeMedium
    Q53.On a straight two-lane highway, a bus 12 m long travelling at 72 km/h overtakes a truck 18 m long travelling at 54 km/h in the same direction. Overtaking starts when the front of the bus is level with the rear of the truck and ends when the rear of the bus is level with the front of the truck. Both speeds stay constant. How long does the overtaking take?
    1. (A)0.86 s
    2. (B)2.4 s
    3. (C)3.6 s
    4. (D)6.0 s
  54. PhysicsMotion in a Straight Line·AccelerationMedium
    Q54.Read the Assertion (A) and Reason (R) about a ball thrown vertically upward, with air resistance neglected, and choose the correct option.
    • Assertion (A): At the highest point of its flight, the acceleration of the ball is zero.
    • Reason (R): At the highest point of its flight, the velocity of the ball is zero.
    1. (A)Both A and R are true, and R is the correct explanation of A
    2. (B)Both A and R are true, but R is not the correct explanation of A
    3. (C)A is true, but R is false
    4. (D)A is false, but R is true
  55. PhysicsMotion in a Straight Line·Velocity-time graph and uniformly accelerated motionHard
    Q55.A car starts from rest on a straight road and accelerates uniformly at 2 m s⁻² for some time. It then brakes immediately with a uniform deceleration of 4 m s⁻² until it stops. The whole journey, from start to stop, lasts 12 s. What total distance does the car cover?
    1. (A)72 m
    2. (B)96 m
    3. (C)108 m
    4. (D)192 m
  56. PhysicsMotion in a Straight Line·Instantaneous velocity; distance vs displacementHard
    Q56.A particle moves along the x-axis with position x = 6t² − t³, where x is in metres and t in seconds. What is the total distance (path length) travelled by the particle between t = 0 and t = 6 s?
    1. (A)0 m
    2. (B)32 m
    3. (C)64 m
    4. (D)108 m
  57. ChemistryOrganic Chemistry – Some Basic Principles and Techniques·IUPAC nomenclatureEasy
    Q57.A student draws (CH₃)₂CH–CH₂–CH₃ and is unsure whether it is a straight-chain or branched alkane. What is its correct IUPAC name?
    1. (A)Pentane
    2. (B)2-Methylbutane
    3. (C)Isopentane
    4. (D)3-Methylbutane
  58. ChemistryOrganic Chemistry – Some Basic Principles and Techniques·Purification techniquesEasy
    Q58.Two completely miscible organic liquids have boiling points differing by only 8 K. Which technique is most suitable for separating them?
    1. (A)Simple distillation
    2. (B)Fractional distillation
    3. (C)Steam distillation
    4. (D)Distillation under reduced pressure
  59. ChemistryOrganic Chemistry – Some Basic Principles and Techniques·Inductive effectEasy
    Q59.Among F, Cl, Br, and I, which halogen shows the strongest −I (electron-withdrawing inductive) effect when directly attached to a carbon chain?
    1. (A)F
    2. (B)Cl
    3. (C)Br
    4. (D)I
  60. ChemistryOrganic Chemistry – Some Basic Principles and Techniques·Carbocation stabilityMedium
    Q60.Which of the following carbocations is the most stable: CH₃⁺ (methyl), CH₃–CH₂⁺ (ethyl, 1°), (CH₃)₂CH⁺ (isopropyl, 2°), or (CH₃)₃C⁺ (tert-butyl, 3°)?
    1. (A)CH₃⁺
    2. (B)CH₃–CH₂⁺
    3. (C)(CH₃)₂CH⁺
    4. (D)(CH₃)₃C⁺
  61. ChemistryOrganic Chemistry – Some Basic Principles and Techniques·ResonanceMedium
    Q61.In the acetate ion, CH₃COO⁻, both carbon–oxygen bonds are experimentally found to be equal in length, intermediate between a typical C–O single bond and a C=O double bond. What best explains this observation?
    1. (A)The ion rapidly interconverts between two structures, with the negative charge hopping back and forth between the two oxygens
    2. (B)The two C–O bonds are best described by a resonance hybrid, in which the negative charge and π-electron density are delocalised equally over both oxygens
    3. (C)One C–O bond is truly single and the other truly double, and they only appear equal when measured because of experimental averaging
    4. (D)Both oxygens carry a full unit negative charge simultaneously
  62. ChemistryOrganic Chemistry – Some Basic Principles and Techniques·IsomerismMedium
    Q62.How many structurally isomeric alcohols (compounds containing an –OH group, excluding ethers) have the molecular formula C₄H₁₀O?
    1. (A)2
    2. (B)3
    3. (C)4
    4. (D)7
  63. ChemistryOrganic Chemistry – Some Basic Principles and Techniques·Inductive effectMedium
    Q63.The Assertion (A) and Reason (R) below concern how far the inductive effect reaches along a carbon chain. Read them and choose the option that correctly describes their relationship.
    • Assertion (A): The inductive effect of a substituent becomes negligible after about three bonds along a carbon chain.
    • Reason (R): The inductive effect is a permanent polarisation transmitted through σ bonds, and the displacement of electron density falls off rapidly with each additional bond from the substituent.
    1. (A)Both A and R are true, and R is the correct explanation of A
    2. (B)Both A and R are true, but R is NOT the correct explanation of A
    3. (C)A is true, but R is false
    4. (D)A is false, but R is true
  64. ChemistryOrganic Chemistry – Some Basic Principles and Techniques·Resonance / carbocation stabilityHard
    Q64.Allyl chloride (CH₂=CH–CH₂–Cl) ionises to give the allyl cation, represented by the two resonance structures CH₂=CH–CH₂⁺ ↔ ⁺CH₂–CH=CH₂. Which statement about this cation is correct?
    1. (A)The two resonance structures interconvert rapidly, and the cation exists as one structure at a time
    2. (B)The two structures are of identical energy and contribute equally, so the actual cation is a single delocalised hybrid more stable than either individual contributing structure
    3. (C)Only the first structure is correct, because the positive charge must remain on the carbon nearest the original C–Cl bond
    4. (D)The cation is destabilised relative to a simple (non-allylic) primary carbocation because the positive charge is spread over two carbons
  65. ChemistryOrganic Chemistry – Some Basic Principles and Techniques·IUPAC nomenclatureHard
    Q65.A five-carbon chain carries a C=C double bond and a chlorine atom: CH₃–CH=CH–CHCl–CH₃. The compound has no principal characteristic group (chloro is always cited as a prefix). What is its correct IUPAC name?
    1. (A)4-Chloropent-2-ene
    2. (B)2-Chloropent-3-ene
    3. (C)4-Chloropent-3-ene
    4. (D)3-Chloropent-2-ene
  66. BiologyPhotosynthesis in Higher Plants·Where does photosynthesis take placeEasy
    Q66.Within the chloroplast, the light reactions of photosynthesis and the carbon-fixation reactions occur in two distinct sub-compartments. Where do these two sets of reactions respectively take place?
    1. (A)Light reactions occur in the stroma, while carbon-fixation reactions occur on the thylakoid membrane
    2. (B)Both the light reactions and the carbon-fixation reactions occur exclusively on the outer chloroplast membrane
    3. (C)Light reactions occur on the thylakoid membrane, while carbon-fixation reactions occur in the stroma
    4. (D)Light reactions occur in the mitochondrial matrix, while carbon fixation occurs in the chloroplast stroma
  67. BiologyPhotosynthesis in Higher Plants·Pigments involved in photosynthesisEasy
    Q67.Photosynthetic pigments can be separated into distinct coloured bands by paper chromatography. Among chlorophyll a, chlorophyll b, xanthophyll, and carotenoid, which one is regarded as the chief pigment because it participates directly in converting light energy to chemical energy?
    1. (A)Chlorophyll b
    2. (B)Chlorophyll a
    3. (C)Xanthophyll
    4. (D)Carotenoid
  68. BiologyPhotosynthesis in Higher Plants·Early experiments — van NielMedium
    Q68.Cornelius van Niel studied purple and green sulphur bacteria, which photosynthesise using H₂S instead of H₂O as the hydrogen donor and release sulphur or sulphate, not O₂. He summarised photosynthesis as 2H₂A + CO₂ → 2A + CH₂O + H₂O (in light), where H₂A is the hydrogen donor. What did he infer about the O₂ released by green plants?
    1. (A)It comes from CO₂, because CO₂ is the reactant that green plants and sulphur bacteria share
    2. (B)It comes from H₂O, the hydrogen donor of green plants, and not from CO₂ — an inference later proved using radioisotopic techniques
    3. (C)It comes from chlorophyll, which is broken down during illumination to release oxygen
    4. (D)It is released directly from the ATP molecules synthesised during the light reaction
  69. BiologyPhotosynthesis in Higher Plants·Light reaction — photosystemsMedium
    Q69.Photosystem I and Photosystem II each have a reaction-centre chlorophyll a molecule, named after the wavelength at which it shows its absorption peak. Which of the following correctly pairs each photosystem with its reaction-centre pigment and identifies the photosystem associated with the splitting of water into O₂, H⁺ and electrons?
    1. (A)PSI has reaction centre P680, PSII has reaction centre P700, and water is split at PSI
    2. (B)PSI has reaction centre P700, PSII has reaction centre P680, and water is split at PSII
    3. (C)PSI has reaction centre P700, PSII has reaction centre P680, and water is split at PSI
    4. (D)Both PSI and PSII have the same reaction centre, P680, and water is split where PSI and PSII physically overlap
  70. BiologyPhotosynthesis in Higher Plants·The electron transport — photophosphorylationMedium
    Q70.The light reaction of photosynthesis can proceed along two alternative electron-flow routes through the photosystems, each yielding a different set of products. Evaluate the two statements below on these two routes.
    • Statement I: Non-cyclic photophosphorylation involves both Photosystem I and Photosystem II acting in series and generates ATP, NADPH, and O₂.
    • Statement II: Cyclic photophosphorylation involves only Photosystem I, produces only ATP with no NADPH or O₂ formed, and can occur in regions such as the stroma lamellae, which lack Photosystem II.
    1. (A)Both Statement I and Statement II are correct
    2. (B)Statement I is correct, but Statement II is incorrect
    3. (C)Statement I is incorrect, but Statement II is correct
    4. (D)Both Statement I and Statement II are incorrect
  71. BiologyPhotosynthesis in Higher Plants·Calvin cycle (C₃ pathway)Medium
    Q71.The biosynthetic phase of photosynthesis begins when a specific five-carbon acceptor molecule reacts with CO₂ in the chloroplast stroma. Evaluate the two statements below on this carbon-fixation step.
    • Statement I: The primary CO₂ acceptor of the Calvin cycle is ribulose-1,5-bisphosphate (RuBP), a five-carbon sugar, and the enzyme catalysing its carboxylation is RuBisCO.
    • Statement II: The first stable product formed when CO₂ combines with RuBP is a three-carbon compound, 3-phosphoglyceric acid (3-PGA), which is why this pathway is also called the C₃ pathway.
    1. (A)Both Statement I and Statement II are correct
    2. (B)Statement I is correct, but Statement II is incorrect
    3. (C)Statement I is incorrect, but Statement II is correct
    4. (D)Both Statement I and Statement II are incorrect
  72. BiologyPhotosynthesis in Higher Plants·The C₄ pathwayHard
    Q72.Plants such as maize and sugarcane show Kranz anatomy. They first fix CO₂ in their mesophyll cells using PEP carboxylase (PEPcase), and the Calvin cycle then operates in their bundle sheath cells. Which of the following correctly explains why this two-step strategy gives C₄ plants better productivity than C₃ plants?
    1. (A)PEP carboxylase directly reduces CO₂ to glucose in the mesophyll cells, making the Calvin cycle in the bundle sheath unnecessary
    2. (B)Kranz anatomy allows C₄ plants to run the entire Calvin cycle in the mesophyll cells, while bundle sheath cells only store starch
    3. (C)The C₄ acids formed by PEPcase in the mesophyll are broken down in the bundle sheath cells to release CO₂; this raises the CO₂ concentration at the RuBisCO site, so RuBisCO works as a carboxylase, its oxygenase activity is minimised and photorespiration does not occur
    4. (D)RuBisCO in C₄ plants has evolved a higher affinity for CO₂ than PEP carboxylase, which is why photorespiration never occurs in these plants
  73. BiologyPhotosynthesis in Higher Plants·PhotorespirationHard
    Q73.RuBisCO's active site can bind both CO₂ and O₂, and the relative concentration of the two gases decides which one binds. Evaluate the following Assertion and Reason about what happens in C₃ plants when O₂ binds instead.
    • Assertion (A): Photorespiration in C₃ plants is regarded as a wasteful process that lowers the net amount of CO₂ fixed.
    • Reason (R): In the photorespiratory pathway there is neither synthesis of sugars nor of ATP; instead it results in the release of CO₂ with the utilisation of ATP.
    1. (A)Both A and R are true, and R is the correct explanation of A
    2. (B)Both A and R are true, but R is not the correct explanation of A
    3. (C)A is true, but R is false
    4. (D)A is false, but R is true
  74. BiologyPhotosynthesis in Higher Plants·ATP synthesis — chemiosmotic hypothesisMedium
    Q74.According to the chemiosmotic hypothesis of ATP synthesis in chloroplasts, protons (H⁺) accumulate in a particular compartment during the light reaction, creating a gradient that drives ATP synthase. In which compartment do these protons accumulate, and in which direction do they move to synthesise ATP?
    1. (A)Protons accumulate in the stroma and move into the thylakoid lumen through ATP synthase to synthesise ATP
    2. (B)Protons accumulate inside the thylakoid lumen and move from the lumen, through ATP synthase, into the stroma to synthesise ATP
    3. (C)Protons accumulate in the mitochondrial matrix and diffuse into the chloroplast stroma through ATP synthase
    4. (D)Protons accumulate equally in the stroma and the lumen, so no net gradient or directional flow is needed for ATP synthesis
  75. BiologyPhotosynthesis in Higher Plants·Factors affecting photosynthesisEasy
    Q75.A crop is grown under bright sunlight with adequate water, but the surrounding air has an unusually low CO₂ concentration. According to Blackman's Law of Limiting Factors, what would you expect to happen to the rate of photosynthesis if light intensity is increased further while CO₂ availability stays low?
    1. (A)The rate of photosynthesis would keep increasing in proportion to light intensity, regardless of CO₂ availability, since light is always the master factor
    2. (B)The rate of photosynthesis would show little to no further increase, because CO₂, being the factor nearest its minimal level, is limiting the rate, not light
    3. (C)The rate of photosynthesis would fall to zero immediately, since any deficiency in one factor completely stops the process
    4. (D)The rate of photosynthesis would increase because higher light intensity raises leaf temperature, which increases CO₂ solubility in the mesophyll cells
  76. ChemistrySome Basic Concepts of Chemistry·Mole concept and molar massesEasy
    Q76.How many hydrogen atoms are present in 5.1 g of ammonia (NH₃)? (N = 14 u, H = 1 u, Nᴀ = 6.022 × 10²³ mol⁻¹)
    1. (A)1.807 × 10²³
    2. (B)5.420 × 10²³
    3. (C)7.226 × 10²³
    4. (D)6.022 × 10²²
  77. ChemistrySome Basic Concepts of Chemistry·Uncertainty in measurement: significant figuresEasy
    Q77.A mass is recorded as 0.020300 g. How many significant figures does this reading contain?
    1. (A)3
    2. (B)5
    3. (C)7
    4. (D)6
  78. ChemistrySome Basic Concepts of Chemistry·Limiting reagentMedium
    Q78.5.4 g of aluminium is heated with 14.2 g of chlorine gas. The reaction is 2Al(s) + 3Cl₂(g) → 2AlCl₃(s). What is the maximum mass of AlCl₃ that can be formed? (Al = 27 u, Cl = 35.5 u)
    1. (A)26.7 g
    2. (B)19.6 g
    3. (C)17.8 g
    4. (D)40.1 g
  79. ChemistrySome Basic Concepts of Chemistry·Reactions in solutions: molarityMedium
    Q79.12.0 g of urea (molar mass 60 g mol⁻¹) is dissolved in 200 g of water. The density of the resulting solution is 1.05 g mL⁻¹. What is the molarity of the solution?
    1. (A)0.943 M
    2. (B)0.991 M
    3. (C)1.00 M
    4. (D)1.05 M
  80. ChemistrySome Basic Concepts of Chemistry·Empirical and molecular formulaMedium
    Q80.An organic compound contains 54.5% carbon, 9.1% hydrogen and 36.4% oxygen by mass. Its vapour density (relative to hydrogen) is 44. What is its molecular formula? (C = 12 u, H = 1 u, O = 16 u)
    1. (A)C₂H₄O
    2. (B)C₃H₆O₃
    3. (C)C₄H₄O₂
    4. (D)C₄H₈O₂
  81. ChemistrySome Basic Concepts of Chemistry·Laws of chemical combinationsEasy
    Q81.Which observation is a direct illustration of the law of multiple proportions?
    1. (A)Carbon dioxide made by burning charcoal and carbon dioxide made by heating limestone both contain 27.3% carbon by mass.
    2. (B)In N₂O, NO and NO₂, the masses of oxygen that combine with 28 g of nitrogen are 16 g, 32 g and 64 g respectively.
    3. (C)Two volumes of hydrogen react with one volume of oxygen to give two volumes of water vapour at the same temperature and pressure.
    4. (D)Equal volumes of all gases at the same temperature and pressure contain equal numbers of molecules.
  82. ChemistrySome Basic Concepts of Chemistry·Atomic and molecular massesMedium
    Q82.Consider the following statements: Which of the statements are correct?
    • Statement I: One atomic mass unit (u) is defined as exactly one-twelfth of the mass of one carbon-12 atom.
    • Statement II: The molar mass of a substance in g mol⁻¹ is numerically equal to its molecular (or formula) mass in u.
    • Statement III: One mole of O₂ gas contains 6.022 × 10²³ oxygen atoms.
    • Statement IV: The atomic mass of chlorine is 35.5 u because every chlorine atom has a mass of 35.5 u.
    1. (A)I and II only
    2. (B)I, II and III only
    3. (C)I, II and IV only
    4. (D)II and IV only
  83. ChemistrySome Basic Concepts of Chemistry·Reactions in solutions: molarity to molalityHard
    Q83.An aqueous solution of NaCl is 3.00 M and has a density of 1.25 g mL⁻¹. What is its molality? (Molar mass of NaCl = 58.5 g mol⁻¹)
    1. (A)2.40 m
    2. (B)3.00 m
    3. (C)2.79 m
    4. (D)3.75 m
  84. ChemistrySome Basic Concepts of Chemistry·Stoichiometry with purity and limiting reagentHard
    Q84.25.0 g of a limestone sample that is 80% CaCO₃ by mass (the rest is unreactive) is treated with 200 mL of 1.5 M HCl. CaCO₃(s) + 2HCl(aq) → CaCl₂(aq) + H₂O(l) + CO₂(g) What volume of CO₂ is released? Take the molar volume of a gas under the conditions of the experiment as 22.7 L mol⁻¹. (Ca = 40 u, C = 12 u, O = 16 u)
    1. (A)4.54 L
    2. (B)3.41 L
    3. (C)6.81 L
    4. (D)5.68 L
  85. ChemistryThermodynamics·Internal energy as a state functionEasy
    Q85.Which set contains ONLY state functions?
    1. (A)Heat, work, internal energy
    2. (B)Internal energy, enthalpy, entropy
    3. (C)Work, enthalpy, temperature
    4. (D)Heat, Gibbs energy, pressure
  86. ChemistryThermodynamics·First law of thermodynamicsEasy
    Q86.A gas in a cylinder absorbs 250 J of heat from the surroundings and, in the same process, does 400 J of work on the surroundings by expanding. What is the change in internal energy of the gas?
    1. (A)+650 J
    2. (B)+150 J
    3. (C)−150 J
    4. (D)−650 J
  87. ChemistryThermodynamics·Enthalpy: relation between ΔH and ΔUMedium
    Q87.In a bomb calorimeter at 298 K, the internal energy change for the complete combustion of liquid ethanol is ΔU = −1364.5 kJ mol⁻¹: C₂H₅OH(l) + 3O₂(g) → 2CO₂(g) + 3H₂O(l) What is ΔH for this reaction at 298 K? (R = 8.314 J K⁻¹ mol⁻¹)
    1. (A)−1362.0 kJ mol⁻¹
    2. (B)−1367.0 kJ mol⁻¹
    3. (C)−3842.1 kJ mol⁻¹
    4. (D)−1359.5 kJ mol⁻¹
  88. ChemistryThermodynamics·Hess's law of constant heat summationMedium
    Q88.Use the following data at 298 K to find the standard enthalpy of formation of propane, C₃H₈(g): ΔcH°[C₃H₈(g)] = −2220.0 kJ mol⁻¹ ΔfH°[CO₂(g)] = −393.5 kJ mol⁻¹ ΔfH°[H₂O(l)] = −285.8 kJ mol⁻¹
    1. (A)+103.7 kJ mol⁻¹
    2. (B)+1540.7 kJ mol⁻¹
    3. (C)−4543.7 kJ mol⁻¹
    4. (D)−103.7 kJ mol⁻¹
  89. ChemistryThermodynamics·Gibbs energy and spontaneityEasy
    Q89.A reaction has ΔH > 0 and ΔS > 0, and both are nearly independent of temperature. Under what conditions is the reaction spontaneous at constant pressure?
    1. (A)At all temperatures
    2. (B)Only at low temperatures
    3. (C)Only at high temperatures
    4. (D)At no temperature
  90. ChemistryThermodynamics·Gibbs energy: threshold temperatureMedium
    Q90.A solid decomposes with ΔH° = +178.0 kJ mol⁻¹ and ΔS° = +160.0 J K⁻¹ mol⁻¹. Assuming both are independent of temperature, in which temperature range is the decomposition spontaneous under standard conditions?
    1. (A)Above 1112.5 K
    2. (B)Below 1112.5 K
    3. (C)Above 1.11 K
    4. (D)Above 839.5 K
  91. ChemistryThermodynamics·Work: isothermal reversible expansion of an ideal gasMedium
    Q91.2.0 mol of an ideal gas expands isothermally and reversibly at 300 K from 10.0 L to 100.0 L. What is the work done on the gas? (R = 8.314 J K⁻¹ mol⁻¹)
    1. (A)−4.99 kJ
    2. (B)+11.49 kJ
    3. (C)Zero
    4. (D)−11.49 kJ
  92. ChemistryThermodynamics·Thermodynamic terms and enthalpyHard
    Q92.Consider the following statements and choose the option that lists ALL the correct ones.
    • Statement I: In an adiabatic process q = 0, so the change in internal energy equals the work done on the system (ΔU = wₐd).
    • Statement II: The standard enthalpy of formation of O₃(g) is zero, because ozone is a form of the element oxygen.
    • Statement III: Heat capacity of a sample is an extensive property, whereas its molar heat capacity is an intensive property.
    • Statement IV: For N₂(g) + 3H₂(g) → 2NH₃(g) at constant temperature, with all gases behaving ideally, ΔH is less than ΔU.
    1. (A)I, II and III only
    2. (B)III and IV only
    3. (C)I, III and IV only
    4. (D)I and III only
  93. ChemistryThermodynamics·Bond enthalpyHard
    Q93.Using the mean bond enthalpies below, estimate ΔrH for the gas-phase hydrogenation of ethene: CH₂=CH₂(g) + H₂(g) → CH₃–CH₃(g) C=C: 614 kJ mol⁻¹; C–C: 348 kJ mol⁻¹; C–H: 413 kJ mol⁻¹; H–H: 436 kJ mol⁻¹
    1. (A)−124 kJ mol⁻¹
    2. (B)+124 kJ mol⁻¹
    3. (C)+702 kJ mol⁻¹
    4. (D)−560 kJ mol⁻¹
  94. PhysicsWork, Energy and Power·WorkEasy
    Q94.A box is dragged 8.0 m along a straight horizontal floor by a rope. The rope pulls with a constant force of 25 N directed at 60° above the horizontal. How much work does the rope's force do on the box?
    1. (A)200 J
    2. (B)173 J
    3. (C)100 J
    4. (D)0 J
  95. PhysicsWork, Energy and Power·Kinetic energyEasy
    Q95.The linear momentum of a body of fixed mass increases by 30%. By what percentage does its kinetic energy increase?
    1. (A)30%
    2. (B)60%
    3. (C)69%
    4. (D)9%
  96. PhysicsWork, Energy and Power·CollisionsEasy
    Q96.Read the Assertion (A) and Reason (R) about a one-dimensional elastic collision between two bodies of different masses, and choose the correct option.
    • Assertion (A): In an elastic collision, the kinetic energy of each colliding body is the same before and after the collision.
    • Reason (R): In an elastic collision, the total kinetic energy of the system is the same before and after the collision.
    1. (A)Both A and R are true, and R is the correct explanation of A
    2. (B)Both A and R are true, but R is not the correct explanation of A
    3. (C)A is true, but R is false
    4. (D)A is false, but R is true
  97. PhysicsWork, Energy and Power·Potential energy of a springMedium
    Q97.A 0.50 kg block slides at 2.0 m/s on a smooth horizontal surface and runs head-on into the free end of a light horizontal spring of spring constant 200 N/m. The other end of the spring is fixed to a wall. What is the maximum compression of the spring?
    1. (A)14.1 cm
    2. (B)10.0 cm
    3. (C)7.1 cm
    4. (D)0.5 cm
  98. PhysicsWork, Energy and Power·PowerMedium
    Q98.An electric pump lifts 200 kg of water through a vertical height of 15 m every minute, delivering it at negligible speed. The pump is 75% efficient. Take g = 10 m s⁻². What is the electrical power input to the pump?
    1. (A)375 W
    2. (B)500 W
    3. (C)667 W
    4. (D)30 000 W
  99. PhysicsWork, Energy and Power·Work-energy theoremMedium
    Q99.A 2.0 kg block is given an initial speed of 6.0 m/s along a rough horizontal floor and slides to rest. The coefficient of kinetic friction between the block and the floor is 0.30. Take g = 10 m s⁻². How far does the block slide?
    1. (A)2.0 m
    2. (B)6.0 m
    3. (C)12 m
    4. (D)60 m
  100. PhysicsWork, Energy and Power·Conservative forces and potential energyMedium
    Q100.The four claims I to IV below concern conservative forces, potential energy and mechanical energy. Pick the option listing exactly the true claims.
    • I. The work done by a conservative force on a body moving around any closed path is zero.
    • II. A potential energy function can be defined only for a conservative force.
    • III. The total mechanical energy of a body remains constant even while kinetic friction acts on it.
    • IV. The work done by a conservative force depends only on the initial and final positions of the body.
    1. (A)I and IV only
    2. (B)I, II and IV only
    3. (C)I, III and IV only
    4. (D)II and III only
  101. PhysicsWork, Energy and Power·Collisions (elastic collision in one dimension)Hard
    Q101.A 2 kg ball moving at 6 m/s on a smooth horizontal track collides head-on, elastically, with a 4 kg ball that is at rest. What fraction of the first ball's initial kinetic energy is transferred to the 4 kg ball?
    1. (A)1
    2. (B)8/9
    3. (C)1/2
    4. (D)2/3
  102. PhysicsWork, Energy and Power·Conservation of mechanical energy with frictionHard
    Q102.A 0.50 kg block is released from rest at a height of 1.8 m on a smooth curved ramp. At the bottom, the ramp joins a horizontal floor. The block first crosses a rough strip of the floor 2.0 m long, where the coefficient of kinetic friction is 0.20. After that the floor is smooth. On the smooth part, the block runs into a light horizontal spring of spring constant 400 N/m with its far end fixed. Take g = 10 m s⁻². What is the maximum compression of the spring?
    1. (A)0.13 m
    2. (B)0.16 m
    3. (C)0.19 m
    4. (D)0.21 m
  103. PhysicsCurrent Electricity·Drift of electrons and the origin of resistivityEasy
    Q103.A copper wire of uniform cross-sectional area 2.5 mm² carries a steady current of 4.0 A. The number density of free electrons in copper is 8.0 × 10²⁸ m⁻³ and the electronic charge is 1.6 × 10⁻¹⁹ C. What is the drift speed of the free electrons?
    1. (A)1.25 × 10⁻⁷ m s⁻¹ (0.000125 mm s⁻¹)
    2. (B)1.25 × 10⁻⁴ m s⁻¹ (0.125 mm s⁻¹)
    3. (C)1.25 × 10⁻⁶ m s⁻¹ (0.00125 mm s⁻¹)
    4. (D)About 3 × 10⁸ m s⁻¹
  104. PhysicsCurrent Electricity·Ohm's law and resistivityEasy
    Q104.A uniform metal wire has a resistance of 8.0 Ω. It is drawn out uniformly so that its length becomes 25% greater than before, with its volume and resistivity unchanged. What is its new resistance?
    1. (A)10.0 Ω
    2. (B)12.5 Ω
    3. (C)15.6 Ω
    4. (D)5.12 Ω
  105. PhysicsCurrent Electricity·Temperature dependence of resistivityEasy
    Q105.A coil of metal wire has a resistance of 20.0 Ω at 20 °C. The temperature coefficient of resistivity of the metal (taking 20 °C as the reference temperature) is 4.0 × 10⁻³ °C⁻¹. Neglecting thermal expansion of the wire, what is the resistance of the coil at 70 °C?
    1. (A)24.0 Ω
    2. (B)25.6 Ω
    3. (C)47.4 Ω
    4. (D)4.0 Ω
  106. PhysicsCurrent Electricity·Cells, emf, internal resistanceMedium
    Q106.A cell of unknown emf E and internal resistance r is connected in series with an ideal ammeter and a 5.0 Ω resistor; the ammeter reads 0.50 A. The 5.0 Ω resistor is then replaced by an 11.0 Ω resistor (nothing else changes) and the ammeter reads 0.25 A. What are E and r?
    1. (A)E = 2.5 V, r = 0 Ω
    2. (B)E = 3.0 V, r = 1.0 Ω
    3. (C)E = 2.0 V, r = 1.0 Ω
    4. (D)E = 2.75 V, r = 1.0 Ω
  107. PhysicsCurrent Electricity·Wheatstone bridgeMedium
    Q107.Four resistors are joined to form a closed quadrilateral ABCD: 2 Ω between A and B, 4 Ω between B and C, 6 Ω between C and D, and 3 Ω between D and A. A fifth resistor of 5 Ω is connected directly between B and D. What is the equivalent resistance of the network between terminals A and C?
    1. (A)3.6 Ω
    2. (B)2.1 Ω
    3. (C)8.6 Ω
    4. (D)15 Ω
  108. PhysicsCurrent Electricity·Cells in series and in parallelHard
    Q108.Two cells are connected in parallel: their positive terminals are joined to one junction and their negative terminals to another. Cell 1 has emf 6.0 V and internal resistance 1.0 Ω; cell 2 has emf 4.0 V and internal resistance 2.0 Ω. A 4.0 Ω resistor is connected between the two junctions. What is the current through the 4.0 Ω resistor?
    1. (A)1.43 A
    2. (B)0.29 A
    3. (C)1.14 A
    4. (D)1.07 A
  109. PhysicsCurrent Electricity·Electrical energy, powerMedium
    Q109.Bulb P is rated 100 W, 200 V and bulb Q is rated 25 W, 200 V. The two bulbs are connected in series across a 200 V supply. Assuming each bulb's resistance stays equal to its value at rated operation, what power is dissipated in bulb Q?
    1. (A)25 W
    2. (B)20 W
    3. (C)16 W
    4. (D)4 W
  110. PhysicsCurrent Electricity·Electric currents in conductorsMedium
    Q110.Read the Assertion (A) and Reason (R) about a copper wire whose cross-section tapers steadily from 2 mm² at one end to 1 mm² at the other end, carrying a steady current. Choose the correct option.
    • Assertion (A): The drift speed of the free electrons at the 1 mm² end is twice their drift speed at the 2 mm² end.
    • Reason (R): In steady state the same current I crosses every cross-section of the wire, and I = neAv_d with the free-electron density n the same throughout the copper.
    1. (A)Both A and R are true and R is the correct explanation of A
    2. (B)Both A and R are true but R is not the correct explanation of A
    3. (C)A is true but R is false
    4. (D)A is false but R is true
  111. PhysicsCurrent Electricity·Kirchhoff's rulesHard
    Q111.An ideal 12 V battery (no internal resistance) has its positive terminal connected to junction A and its negative terminal to junction C. Two branches join A to C: branch 1 runs A → B → C with 2.0 Ω between A and B and 4.0 Ω between B and C; branch 2 runs A → D → C with 4.0 Ω between A and D and 2.0 Ω between D and C. A 2.0 Ω resistor is connected directly between junctions B and D. What is the current in the B–D resistor?
    1. (A)Zero
    2. (B)0.86 A, from B to D
    3. (C)0.86 A, from D to B
    4. (D)2.0 A, from B to D
  112. BiologyHuman Reproduction·The Male Reproductive SystemEasy
    Q112.Within the seminiferous tubules of the human testis, which cells provide nutrition to the developing germ cells and are regulated by the pituitary hormone FSH?
    1. (A)Leydig cells
    2. (B)Sertoli cells
    3. (C)Primary spermatocytes
    4. (D)Spermatogonia
  113. BiologyHuman Reproduction·The Female Reproductive SystemEasy
    Q113.In humans, fertilisation of the ovum by a sperm normally occurs in which part of the female reproductive tract?
    1. (A)The uterine cavity
    2. (B)The ampullary region of the fallopian tube (oviduct)
    3. (C)The cervix
    4. (D)The ovary itself, immediately after ovulation
  114. BiologyHuman Reproduction·Gametogenesis — SpermatogenesisEasy
    Q114.One primary spermatocyte undergoes meiosis I followed by meiosis II. How many functional, haploid spermatids does a single primary spermatocyte ultimately give rise to?
    1. (A)Two
    2. (B)Four
    3. (C)Eight
    4. (D)One
  115. BiologyHuman Reproduction·Gametogenesis — OogenesisMedium
    Q115.During oogenesis, the primary oocyte completes meiosis I just before ovulation. This first meiotic division is markedly unequal in terms of cytoplasm distribution. What are the two products of this division?
    1. (A)Two secondary oocytes of equal size
    2. (B)A large secondary oocyte and a small first polar body
    3. (C)A secondary oocyte and a second polar body
    4. (D)Two first polar bodies, one of which later enlarges into the ovum
  116. BiologyHuman Reproduction·Menstrual CycleMedium
    Q116.Around the 14th day of a typical 28-day menstrual cycle, a sharp mid-cycle surge of a pituitary hormone triggers rupture of the Graafian follicle and release of the secondary oocyte. Which hormone surge is directly responsible for triggering ovulation?
    1. (A)A surge of follicle-stimulating hormone (FSH) alone
    2. (B)A surge of luteinising hormone (LH)
    3. (C)A surge of progesterone from the corpus luteum
    4. (D)A surge of estrogen from the corpus luteum
  117. BiologyHuman Reproduction·Menstrual CycleMedium
    Q117.Consider the following statements about the phases of the human menstrual cycle. Which one/ones is/are correct?
    • Statement I: During the follicular (proliferative) phase, the growing Graafian follicle secretes estrogen, which causes the uterine endometrium to regenerate and thicken.
    • Statement II: During the luteal (secretory) phase, the corpus luteum secretes progesterone, which further prepares the endometrium to receive and support a possible embryo.
    1. (A)Statement I only
    2. (B)Statement II only
    3. (C)Both Statement I and Statement II
    4. (D)Neither Statement I nor Statement II
  118. BiologyHuman Reproduction·Fertilisation and ImplantationMedium
    Q118.During fertilisation in humans, a sperm reaches the ovum in the ampullary region of the fallopian tube. Regarding the events that follow, which statement(s) is/are correct?
    • Statement I: Entry of the sperm into the secondary oocyte induces it to complete its second meiotic division, which is unequal and forms a second polar body and a haploid ovum (ootid).
    • Statement II: A sperm coming in contact with the zona pellucida layer of the ovum induces changes in the membrane that block the entry of additional sperms, ensuring that only one sperm fertilises an ovum.
    1. (A)Statement I only
    2. (B)Statement II only
    3. (C)Both Statement I and Statement II
    4. (D)Neither Statement I nor Statement II
  119. BiologyHuman Reproduction·Pregnancy and Embryonic DevelopmentHard
    Q119.The placenta acts as an endocrine tissue during pregnancy. Read the Assertion and Reason below about human chorionic gonadotropin (hCG), judge whether each is true, and select the option that correctly relates them.
    • Assertion (A): The presence of human chorionic gonadotropin (hCG) in a woman's body can be used as an indicator of pregnancy.
    • Reason (R): hCG is secreted by the placenta and, like hPL and relaxin, is produced in women only during pregnancy.
    1. (A)Both A and R are true, and R is the correct explanation of A
    2. (B)Both A and R are true, but R is not the correct explanation of A
    3. (C)A is true, but R is false
    4. (D)A is false, but R is true
  120. BiologyHuman Reproduction·Parturition and LactationMedium
    Q120.Parturition (childbirth) is initiated by signals that originate mainly from the fully developed foetus and the placenta, producing mild uterine contractions known as the 'foetal ejection reflex.' Which hormone's release is progressively amplified during labour through a positive feedback loop with these uterine contractions?
    1. (A)Progesterone
    2. (B)Oxytocin
    3. (C)Human chorionic gonadotropin (hCG)
    4. (D)Follicle-stimulating hormone (FSH)
  121. BiologyHuman Reproduction·Hormones of the Reproductive SystemHard
    Q121.Match the hormone in Column I with its correct source and a key role or feature in Column II, then choose the option in which all four matches are correct.
    Column I
    Column II
    P. Follicle-stimulating hormone (FSH)
    1. Secreted by the placenta; produced in women only during pregnancy
    Q. Luteinising hormone (LH)
    2. Secreted by the anterior pituitary; acts on Leydig cells to stimulate androgen secretion and, at its mid-cycle surge, induces ovulation
    R. Human chorionic gonadotropin (hCG)
    3. Secreted by the anterior pituitary; acts on Sertoli cells and stimulates growth of ovarian follicles
    S. Prolactin
    4. Secreted by the anterior pituitary; regulates growth of the mammary glands and formation of milk in them
    1. (A)P-3, Q-2, R-1, S-4
    2. (B)P-2, Q-3, R-1, S-4
    3. (C)P-3, Q-2, R-4, S-1
    4. (D)P-3, Q-1, R-2, S-4
  122. BiologyMolecular Basis of Inheritance·Structure of DNAEasy
    Q122.The two strands of a DNA double helix are held together by hydrogen bonds between complementary nitrogenous bases. A cytosine on one strand always pairs with which base on the complementary strand, and through how many hydrogen bonds?
    1. (A)Guanine, through two hydrogen bonds
    2. (B)Guanine, through three hydrogen bonds
    3. (C)Thymine, through two hydrogen bonds
    4. (D)Adenine, through three hydrogen bonds
  123. BiologyMolecular Basis of Inheritance·Structure of DNAEasy
    Q123.The two polynucleotide strands of a DNA double helix run in opposite directions, one 5'→3' and the other 3'→5'. This arrangement of the two strands is described as:
    1. (A)Complementary
    2. (B)Semiconservative
    3. (C)Antiparallel
    4. (D)Discontinuous
  124. BiologyMolecular Basis of Inheritance·The Search for Genetic MaterialMedium
    Q124.In Frederick Griffith's experiment, mice injected with a mixture of heat-killed S-strain (smooth, virulent) Streptococcus pneumoniae and live R-strain (rough, non-virulent) bacteria died, and living S-strain bacteria were recovered from the dead mice. What did Griffith conclude from this result?
    1. (A)Heat-killed S-strain bacteria had regained virulence on their own after injection
    2. (B)Some 'transforming principle' from the dead S-strain had been transferred to and had genetically transformed the living R-strain
    3. (C)The R-strain bacteria mutated spontaneously into the S-strain due to the stress of infection
    4. (D)Heat-killed S-strain and live R-strain bacteria acted together as separate agents to kill the mouse without any exchange of material
  125. BiologyMolecular Basis of Inheritance·The Genetic Material is DNA — Hershey-Chase experimentMedium
    Q125.Hershey and Chase used bacteriophages labelled separately with radioactive sulphur (³⁵S) and radioactive phosphorus (³²P) to infect E. coli, then agitated the mixture in a blender before centrifuging. Which observation confirmed that DNA, and not protein, is the genetic material?
    1. (A)³⁵S entered the bacterial cells and was passed on to the phage progeny
    2. (B)Bacteria infected with ³²P-labelled phages became radioactive, while bacteria infected with ³⁵S-labelled phages did not
    3. (C)Both ³⁵S and ³²P entered the bacterial cells in equal amounts, showing that protein and DNA act together as genetic material
    4. (D)Neither isotope entered the bacterial cells, showing that phage infection occurs without any genetic material entering the host
  126. BiologyMolecular Basis of Inheritance·Replication — Meselson-Stahl experimentHard
    Q126.E. coli cells were grown for many generations in a medium containing only the heavy nitrogen isotope ¹⁵N, so that all their DNA became fully heavy (¹⁵N/¹⁵N). The cells were then shifted to a medium containing only the light isotope ¹⁴N and allowed to divide exactly three times. Assuming semiconservative replication, what fraction of the DNA molecules present after the third division is completely light (¹⁴N/¹⁴N)?
    1. (A)1/2
    2. (B)1/4
    3. (C)3/4
    4. (D)7/8
  127. BiologyMolecular Basis of Inheritance·Replication — enzymes and Okazaki fragmentsMedium
    Q127.DNA polymerase can add nucleotides only in the 5'→3' direction. Because the two template strands at a replication fork are antiparallel, one new strand (the lagging strand) cannot be synthesised continuously. How is the lagging strand actually made?
    1. (A)As one long continuous strand synthesised in the 3'→5' direction
    2. (B)As short fragments called Okazaki fragments, synthesised discontinuously and later joined by DNA ligase
    3. (C)By RNA polymerase, which replaces DNA polymerase on the lagging strand only
    4. (D)It is not synthesised during replication; only the leading strand is copied, and the lagging strand is retained from the parent unchanged
  128. BiologyMolecular Basis of Inheritance·Transcription UnitHard
    Q128.RNA polymerase transcribes only one strand of a DNA segment, even though the DNA is double-stranded. Read the Assertion and Reason below on why transcription is restricted to a single strand, and choose the correct option.
    • Assertion (A): Within a transcription unit, only one of the two DNA strands (the template strand) is transcribed into RNA.
    • Reason (R): If both strands were transcribed at the same time, the two RNA molecules formed would be complementary to each other and would pair into a double-stranded RNA that could not be translated into protein.
    1. (A)Both A and R are true, and R is the correct explanation of A
    2. (B)Both A and R are true, but R is not the correct explanation of A
    3. (C)A is true, but R is false
    4. (D)A is false, but R is true
  129. BiologyMolecular Basis of Inheritance·Genetic CodeMedium
    Q129.Two statements about the genetic code are given below. Which one/ones is/are correct?
    • Statement I: The genetic code is degenerate, meaning a single amino acid can be specified by more than one codon.
    • Statement II: The genetic code is ambiguous, meaning a single codon can specify more than one amino acid.
    1. (A)Statement I only
    2. (B)Statement II only
    3. (C)Both Statement I and Statement II
    4. (D)Neither Statement I nor Statement II
  130. BiologyMolecular Basis of Inheritance·Regulation of Gene Expression — the lac operonMedium
    Q130.Consider the following statements about regulation of the lac operon in E. coli. Which one/ones is/are correct?
    • Statement I: In the absence of an inducer such as lactose, the repressor protein made by the i gene binds to the operator region and prevents RNA polymerase from transcribing the structural genes.
    • Statement II: The inducer (lactose or allolactose) switches the operon on by binding directly to the operator DNA and physically pushing the repressor off it.
    1. (A)Statement I only
    2. (B)Statement II only
    3. (C)Both Statement I and Statement II
    4. (D)Neither Statement I nor Statement II
  131. BiologyMolecular Basis of Inheritance·DNA FingerprintingEasy
    Q131.DNA fingerprinting relies on comparing regions of the genome that show a high degree of polymorphism (variation) between individuals. Which class of DNA sequence is exploited for this purpose?
    1. (A)Structural genes coding for enzymes of central metabolism
    2. (B)Repetitive DNA sequences that show a variable number of tandem repeats (satellite/VNTR DNA)
    3. (C)The promoter sequences of housekeeping genes
    4. (D)Ribosomal RNA gene sequences, which are identical in all individuals of a species
  132. BiologyPrinciples of Inheritance and Variation·Mendel's Laws of InheritanceEasy
    Q132.Mendel crossed a true-breeding tall pea plant (TT) with a true-breeding dwarf pea plant (tt). All F₁ plants were tall, but when the F₁ plants were self-pollinated, dwarf plants reappeared in F₂, exactly as dwarf as the original dwarf parent, with no blending. Which Mendelian law is based on this recovery of the parental characters unchanged in F₂, and explains it by the separation of the two alleles into different gametes?
    1. (A)Law of Independent Assortment
    2. (B)Law of Dominance
    3. (C)Law of Segregation
    4. (D)Law of Co-dominance
  133. BiologyPrinciples of Inheritance and Variation·Mendel's Laws of InheritanceEasy
    Q133.A pea plant with the genotype Tt is grown and its outward height (tall) is recorded. With respect to the height gene, this plant is best described as:
    1. (A)Homozygous dominant
    2. (B)Homozygous recessive
    3. (C)Heterozygous
    4. (D)Hemizygous
  134. BiologyPrinciples of Inheritance and Variation·Inheritance of Two GenesMedium
    Q134.In garden pea, round seed shape (R) is dominant over wrinkled (r), and yellow seed colour (Y) is dominant over green (y); the two genes assort independently. A dihybrid F₁ plant of genotype RrYy is self-pollinated to raise 1,600 F₂ seeds. Based on the expected 9:3:3:1 ratio, how many of these F₂ seeds are expected to be wrinkled and yellow?
    1. (A)100
    2. (B)300
    3. (C)900
    4. (D)1200
  135. BiologyPrinciples of Inheritance and Variation·Deviations from Mendelism — Incomplete DominanceMedium
    Q135.In the dog flower (snapdragon, Antirrhinum sp.), flower colour shows incomplete dominance: a true-breeding red-flowered plant (RR) crossed with a true-breeding white-flowered plant (rr) gives pink-flowered F₁ plants (Rr). If these pink F₁ plants are self-pollinated, what phenotypic ratio is expected among the F₂ plants?
    1. (A)3 red : 1 white
    2. (B)1 red : 2 pink : 1 white
    3. (C)1 red : 1 pink : 2 white
    4. (D)9 red : 3 pink : 4 white
  136. BiologyPrinciples of Inheritance and Variation·Deviations from Mendelism — Multiple AllelesMedium
    Q136.The ABO blood group in humans is controlled by multiple alleles IA, IB and i, where IA and IB are co-dominant and both are dominant over i. A man with blood group A (genotype IAi) marries a woman with blood group B (genotype IBi). What proportion of their children is expected to have blood group O?
    1. (A)0
    2. (B)1/4
    3. (C)1/2
    4. (D)1
  137. BiologyPrinciples of Inheritance and Variation·Chromosomal Theory of Inheritance — Linkage and RecombinationMedium
    Q137.With respect to linkage and recombination, which statement(s) is/are correct?
    • Statement I: Genes located far apart on the same chromosome show a higher recombination frequency than genes located close together on that chromosome.
    • Statement II: Linked genes located on the same chromosome always show 100% recombination in every generation, identical to genes located on different chromosomes.
    1. (A)Statement I only
    2. (B)Statement II only
    3. (C)Both Statement I and Statement II
    4. (D)Neither Statement I nor Statement II
  138. BiologyPrinciples of Inheritance and Variation·Sex DeterminationMedium
    Q138.Regarding sex-determination mechanisms, which statement(s) is/are correct?
    • Statement I: In humans, sex is determined by whether a sperm carrying an X or a Y chromosome fertilises the egg, making the male the heterogametic sex.
    • Statement II: In birds, males are heterogametic (ZW) and females are homogametic (ZZ), the mirror image of the human XY system.
    1. (A)Statement I only
    2. (B)Statement II only
    3. (C)Both Statement I and Statement II
    4. (D)Neither Statement I nor Statement II
  139. BiologyPrinciples of Inheritance and Variation·Pedigree Analysis and Mendelian DisordersHard
    Q139.Haemophilia is a sex-linked disorder in which a single protein of the blood-clotting cascade is affected, so even a small cut can bleed without stopping. Evaluate the Assertion about how often the disorder appears in each sex and the Reason offered for it.
    • Assertion (A): Haemophilia is much more commonly observed in human males than in human females.
    • Reason (R): Haemophilia is caused by a recessive allele located on the X chromosome, so a male needs only one copy of the allele to be affected, whereas a female needs two copies.
    1. (A)Both A and R are true, and R is the correct explanation of A
    2. (B)Both A and R are true, but R is not the correct explanation of A
    3. (C)A is true, but R is false
    4. (D)A is false, but R is true
  140. BiologyPrinciples of Inheritance and Variation·Mendelian Disorders — Sickle-cell AnaemiaEasy
    Q140.Sickle-cell anaemia is caused by the substitution of a single amino acid in the beta-globin chain of haemoglobin, which makes red blood cells become rigid and sickle-shaped under low-oxygen conditions. What inheritance pattern does this disorder show?
    1. (A)X-linked dominant
    2. (B)Autosomal dominant
    3. (C)Autosomal recessive
    4. (D)Y-linked
  141. BiologyPrinciples of Inheritance and Variation·Chromosomal DisordersHard
    Q141.Match the condition in Column I with its correct karyotype/chromosomal basis in Column II, then choose the option in which all four matches are correct.
    Column I
    Column II
    P. Down syndrome
    1. 47, XXY (an extra X chromosome in a male)
    Q. Klinefelter syndrome
    2. 45, X0 (a single X chromosome, no second sex chromosome)
    R. Turner syndrome
    3. Trisomy 21 — 47 chromosomes, an extra copy of chromosome 21
    S. Normal human female karyotype
    4. 46, XX
    1. (A)P-3, Q-1, R-2, S-4
    2. (B)P-1, Q-3, R-2, S-4
    3. (C)P-3, Q-2, R-1, S-4
    4. (D)P-3, Q-1, R-4, S-2
  142. PhysicsRay Optics and Optical Instruments·Reflection of light by spherical mirrorsEasy
    Q142.An object is placed on the principal axis 30 cm in front of a concave mirror of focal length 20 cm. Using the Cartesian sign convention, where and what kind of image is formed?
    1. (A)12 cm in front of the mirror; real, inverted, magnification −0.4
    2. (B)60 cm in front of the mirror; real, inverted, magnification −2
    3. (C)60 cm behind the mirror; virtual, erect, magnification +2
    4. (D)12 cm behind the mirror; virtual, erect, magnification +0.4
  143. PhysicsRay Optics and Optical Instruments·Total internal reflectionEasy
    Q143.Light travels at 2.0 × 10⁸ m s⁻¹ in a certain transparent solid and at 3.0 × 10⁸ m s⁻¹ in air. What is the critical angle for light going from the solid towards its boundary with air?
    1. (A)33.7°
    2. (B)41.8°
    3. (C)48.2°
    4. (D)56.3°
  144. PhysicsRay Optics and Optical Instruments·Power of a lens and combination of thin lenses in contactEasy
    Q144.A thin converging lens of focal length 25 cm is placed in contact with a thin diverging lens of focal length 40 cm (both focal lengths given as magnitudes). What is the power of the combination?
    1. (A)+6.5 D (converging)
    2. (B)−1.5 D (diverging)
    3. (C)+0.015 D
    4. (D)+1.5 D (converging)
  145. PhysicsRay Optics and Optical Instruments·Refraction: apparent depthMedium
    Q145.A coin lies at the bottom of a tank. The tank holds a 24 cm deep layer of water (refractive index 4/3), and on top of the water floats a 15 cm thick layer of a transparent oil (refractive index 1.50). Viewed from air almost vertically above (near-normal incidence), how far below the top surface of the oil does the coin appear to be?
    1. (A)11 cm
    2. (B)28 cm
    3. (C)33 cm
    4. (D)54.5 cm
  146. PhysicsRay Optics and Optical Instruments·Refraction by a lens: lensmaker's formulaMedium
    Q146.A thin biconvex lens of glass (refractive index 1.50) has radii of curvature 20 cm and 30 cm for its two faces. Its focal length in air is 24 cm. The lens is completely immersed in a transparent liquid of refractive index 1.25. What is its focal length in the liquid?
    1. (A)24 cm
    2. (B)48 cm
    3. (C)60 cm
    4. (D)300 cm
  147. PhysicsRay Optics and Optical Instruments·Refraction through a prismMedium
    Q147.A glass prism has a refracting angle of 60°. For monochromatic light, the angle of minimum deviation is measured to be 38°. What is the refractive index of the glass?
    1. (A)1.14
    2. (B)1.23
    3. (C)1.51
    4. (D)1.63
  148. PhysicsRay Optics and Optical Instruments·Optical instruments: telescopeMedium
    Q148.Consider the following statements about a refracting astronomical telescope used in normal adjustment (final image at infinity). Which of the statements are correct?
    • I. The distance between the objective and the eyepiece equals f_o + f_e.
    • II. Its magnifying power is f_o/f_e, so the objective should have a much larger focal length than the eyepiece.
    • III. Increasing the diameter of the objective (keeping its focal length unchanged) increases the magnifying power.
    • IV. The final image seen through the telescope is erect.
    1. (A)I and II only
    2. (B)I, II and III only
    3. (C)II and IV only
    4. (D)I, III and IV only
  149. PhysicsRay Optics and Optical Instruments·Optical instruments: compound microscopeHard
    Q149.A compound microscope has an objective of focal length 1.0 cm and an eyepiece of focal length 4.0 cm. An object is placed 1.2 cm in front of the objective, and the eyepiece is adjusted so that the final image forms at the least distance of distinct vision, 25 cm from the eyepiece (the eye is held close to the eyepiece). What is the magnitude of the magnifying power?
    1. (A)31.25
    2. (B)36.25
    3. (C)43.5
    4. (D)59.1
  150. PhysicsRay Optics and Optical Instruments·Refraction by lenses: image by successive lensesHard
    Q150.A thin converging lens L₁ of focal length 20 cm and a thin diverging lens L₂ of focal length 30 cm (magnitude) are placed coaxially 40 cm apart, with L₂ to the right of L₁. An object is placed on the axis 30 cm to the left of L₁, and light travels from left to right. Using the Cartesian sign convention, where is the final image formed?
    1. (A)60 cm to the right of L₂; real, inverted, 6 times the object size
    2. (B)12 cm to the left of L₂; virtual, inverted, 1.2 times the object size
    3. (C)20 cm to the right of L₂; real, inverted, 2 times the object size
    4. (D)60 cm to the left of the lens pair; virtual, erect, 2 times the object size

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