Model Paper 2

Chapter 3 · Full Model Papers · 200 questions in the paper · 34 min read

Model Paper 2

What the syllabus asks for 1
  • Zoology 40, Botany 40, Chemistry 50, Physics 50, Mental Agility Test 20, with an explained key

MODEL PAPER 2 — MECEE-BL (Group I). Time: 3 hours. Full marks: 200. Attempt all questions. Each question has four options with one best answer; choose the best and mark it on your answer grid. Each correct answer carries 1 mark and each wrong answer deducts 0.25 mark. Calculators are not allowed; do rough work in the margins. Sit this paper in one uninterrupted sitting, exactly as on the day.

How to score yourself: score = (number correct) − 0.25 × (number wrong). Do not leave blanks — in this marking scheme even a blind guess is worth +1/16 of a mark. Record your correct/wrong/blank counts per subject before you open the key.

This paper follows the official unit weightage exactly:

Subject Qs Per-unit counts in this paper
Zoology 40 Evolution 3 · Diversity 4 · Tissues 4 · Selected animals 6 · Digestive 2 · Respiratory 2 · Circulatory 3 · Excretory 2 · Nervous 2 · Endocrine 2 · Reproductive 2 · Diseases/Immunity 4 · Medical technology 2 · Environment 2
Botany 40 Components of life 2 · Virus/bacteria 2 · Fungi/lichens 2 · Algae/bryophytes 2 · Pteridophytes–angiosperms 3 · Ecology 4 · Cell biology 5 · Genetics fundamentals 2 · Genetic material 4 · Anatomy 3 · Water relations 2 · Photosynthesis/respiration 3 · Growth 1 · Developmental 2 · Applied 3
Chemistry 50 Physical 17 · Inorganic 10 · Organic 17 · Applied 3 · Analytical 3
Physics 50 Mechanics 10 · Heat 7 · Waves/Optics 8 · Current electricity/Magnetism 9 · Electrostatics 4 · Modern 12
MAT 20 Verbal 5 · Numerical 5 · Logical 5 · Spatial/Abstract 5

Zoology (questions 1–40)

  1. Darwin's finches of the Galápagos islands are a classic example ofaindustrial melanismbartificial selectioncparallel evolutiondadaptive radiation
  2. A vestigial organ in human beings is theavermiform appendixbgall bladdercpatelladsternum
  3. The theory of inheritance of acquired characters was proposed byaLamarckbDarwincWeismanndde Vries
  4. The stinging cells of cnidarians (coelenterates) are calledaflame cellsbcnidoblastscchoanocytesdnephridia
  5. Natural pearls are obtained from the oysteraPinctadabPilacSepiadOctopus
  6. Which of the following is a true fish?aSilverfishbJellyfishcSea horse (Hippocampus)dCuttlefish
  7. The egg-laying mammal among the following is theakangaroobplatypuscbatdwhale
  8. A tendon connectsabone to bonebmuscle to musclecnerve to muscledmuscle to bone
  9. The mature cells of bone are calledachondrocytesbfibroblastscosteocytesdneurons
  10. Stratified squamous epithelium is found in theaalveoli of lungsbkidney tubulescepidermis of skindlining of capillaries
  11. Which of the following is not a connective tissue?aBloodbCartilagecAdipose tissuedEpidermis
  12. Ronald Ross demonstrated that malaria is transmitted by theafemale Anopheles mosquitobCulex mosquitocsandflydcontaminated drinking water
  13. The signet-ring stage of Plasmodium is seen in theagut of mosquitobliver cellscsalivary glandsdred blood cells of man
  14. The function of the typhlosole in the earthworm is to increase theaspeed of locomotionbabsorptive surface of the intestinecrate of reproductiondefficiency of excretion
  15. The earthworm respires through itsamoist skinbgillsctracheaedbook lungs
  16. In the male frog, Bidder's canal conveys the sperms through thealiverburinary bladderckidneydcloaca directly
  17. Vocal sacs, which amplify the croaking sound, are present in theafemale frog onlybboth sexes equallycmale frog onlydtadpole only
  18. Gastric pepsin acts most effectively at a pH of abouta7.0b8.5c6.5d1.5–2.0
  19. Villi, which greatly increase the absorptive surface, are present in theastomachbsmall intestineclarge intestinedoesophagus
  20. The volume of air that remains in the lungs even after forceful expiration is theatidal volumebresidual volumecvital capacitydinspiratory reserve volume
  21. Most of the oxygen in the blood is carried in the form ofaoxyhaemoglobinbsolution in plasmaccarbamino compoundsdbicarbonates
  22. The first heart sound ("lub") is produced by the closure of theaatrioventricular valvesbsemilunar valvescEustachian valvedpulmonary valve only
  23. The largest artery of the human body is theacarotid arterybcoronary arterycaortadpulmonary artery
  24. Blood platelets play an essential role inaoxygen transportbclotting of bloodcimmunitydhormone transport
  25. Urea is synthesised in the human body mainly in theakidneyburinary bladdercblooddliver
  26. Glomerular filtration occurs mainly because of theaosmotic pressure of plasmabhydrostatic pressure in glomerular capillariescactive transport by podocytesdsuction of the tubule
  27. Breathing and heart rate are controlled involuntarily by centres in theacerebrumbcerebellumcmedulla oblongatadhypothalamus only
  28. The organ of Corti, the receptor of hearing, is located in theautriclebsemicircular canalscEustachian tubedcochlea
  29. Diabetes mellitus is caused by the deficiency ofaglucagonbadrenalinecinsulindthyroxine
  30. The gland often called the "master gland" of the body is theapituitary glandbthyroid glandcpineal glanddadrenal gland
  31. In human females, fertilisation normally takes place in theauterusbvaginacovarydfallopian tube
  32. The corpus luteum secretes mainly the hormoneaFSHbprogesteronecLHdoxytocin
  33. HIV, the virus that causes AIDS, mainly attacks theaB-lymphocytesbred blood cellscplateletsdhelper T-lymphocytes (CD4 cells)
  34. Rabies is transmitted to human beings most commonly through theabite of a mosquitobdrinking watercairdbite of a rabid dog
  35. Active immunity is the resistance developed when the bodyareceives ready-made antibodies made by another personbproduces its own antibodies after infection or vaccinationcreceives maternal antibodies through the placentadis given an injection of a ready antiserum
  36. Dengue fever is transmitted by the mosquitoaAedes aegyptibAnophelescCulex onlydsandfly
  37. A CT scan forms cross-sectional images of the body usingaultrasoundbstrong magnetscX-raysdradio waves only
  38. Haemodialysis is a treatment used when there is failure of theakidneysbliverclungsdheart
  39. The first national park established in Nepal isaSagarmatha National ParkbChitwan National ParkcBardia National ParkdLangtang National Park
  40. The greenhouse gas contributing most to human-caused global warming isamethanebchlorofluorocarbonsccarbon dioxidednitrous oxide

Botany (questions 41–80)

  1. The amino acids of a protein are joined together byapeptide bondsbglycosidic bondscester bondsdhydrogen bonds only
  2. Complete oxidation of one gram of fat yields abouta4 kcalb7 kcalc9.3 kcald2 kcal
  3. The genetic material of tobacco mosaic virus (TMV) isadouble-stranded DNAbsingle-stranded DNAcsingle-stranded RNAdprotein
  4. Transfer of bacterial genes from one cell to another through a virus is calledaconjugationbtransformationcbinary fissiondtransduction
  5. The antibiotic penicillin was first obtained from the fungusayeastbRhizopuscAgaricusdPenicillium notatum
  6. Lichens are very sensitive indicators of air pollution byacarbon monoxidebsulphur dioxidecmethanedozone only
  7. The cell walls of diatoms are largely made ofacellulosebsilicacchitindagar
  8. Bryophytes are called the amphibians of the plant kingdom because they need water foraphotosynthesisbgrowthcrespirationdfertilisation
  9. Heterospory (two kinds of spores) is shown byaSelaginellabFunariacSpirogyradUlothrix
  10. The special nitrogen-fixing roots of Cycas containing cyanobacteria are theapneumatophoresbprop rootscmycorrhizaedcoralloid roots
  11. A square stem with bilabiate (two-lipped) flowers is characteristic of the familyaSolanaceaebMalvaceaecLamiaceae (mint family)dRosaceae
  12. Secondary succession takes place on an area thatawas previously vegetated but disturbedbconsists of entirely bare, fresh rockcis covered by a recent flow of lavadhas never had any soil formed on it
  13. A food web, compared with a simple food chain, gives the ecosystem greaterastabilitybenergy losscproducer numbersdchance of inversion
  14. Eutrophication of lakes is caused mainly by an excess ofaoxygenbcarbon dioxidecnitrates and phosphatesdcalcium salts
  15. The breathing roots of mangrove plants are calledapneumatophoresbvelamen rootschaustoriadrhizophores
  16. Lysosomes are called "suicidal bags" because they containaDNAbhydrolytic (digestive) enzymescribosomesdphotosynthetic pigments
  17. Chromosomes are arranged on the equatorial plate during the stage of mitosis calledaprophasebmetaphasecanaphasedtelophase
  18. Crossing over between homologous chromosomes occurs during theapachytene stagebleptotene stagecdiakinesis stagedzygotene stage
  19. The nucleolus is principally the site of synthesis ofamRNAbribosomal RNAcDNAdproteins
  20. Endoplasmic reticulum bearing ribosomes on its surface is theasmooth endoplasmic reticulumbrough endoplasmic reticulumcGolgi complexdtonoplast
  21. The phenotypic ratio obtained in the F₂ generation of a dihybrid cross isa3:1b1:2:1c9:3:3:1d1:1:1:1
  22. The ABO blood groups of human beings are an example ofamultiple allelismblinkagecepistasisdpleiotropy
  23. The number of base pairs in one full turn of the B-DNA helix isa8b12c20d10
  24. In a sample of DNA, adenine forms 20% of the bases. The percentage of guanine isa30%b20%c40%d10%
  25. Transcription of DNA into RNA is catalysed by the enzymeaRNA polymerasebDNA polymerasecligasedhelicase
  26. In the wobble hypothesis, the base of the codon that pairs loosely is theafirst basebthird basecsecond basedbase outside the codon
  27. Cork (phellem) of a woody stem is produced by theaphellogen (cork cambium)bvascular cambiumcprocambiumddermatogen
  28. In angiosperms, water is conducted upward mainly through theatracheids onlybvesselscxylem fibresdxylem parenchyma
  29. The vascular bundles of a dicot root are arranged in the pattern calledaconjoint and openbconjoint and closedcradialdbicollateral
  30. The cohesion–tension theory of the ascent of sap was put forward byaErnst MünchbJoseph PriestleycDixon and JolydStephen Hales
  31. Stomata open when the guard cells take in ions that raise their turgor, principallyasodium ionsbcalcium ionscchloride ions onlydpotassium ions
  32. The oxygen released during photosynthesis comes fromacarbon dioxidebglucosecchlorophylldwater
  33. The enzymes of the Krebs cycle are located in the mitochondria within theaouter membranebintermembrane spacecmatrixdribosomes
  34. Anaerobic respiration in yeast converts glucose intoalactic acid onlybcarbon dioxide and watercacetic aciddethanol and carbon dioxide
  35. The plant hormone that promotes seed dormancy and stomatal closure isaauxinbgibberellinccytokinindabscisic acid
  36. The mature pollen grain of an angiosperm represents theasporophyte generationbmale gametophytecembryodendosperm
  37. The typical (Polygonum-type) embryo sac of angiosperms isa8-celled and 7-nucleateb6-celled and 6-nucleatec7-celled and 8-nucleated8-celled and 8-nucleate
  38. Golden Rice has been genetically engineered to be rich inaironbproteincvitamin Cdbeta-carotene (provitamin A)
  39. The aquatic fern used as a biofertiliser in paddy fields isaMarsileabAzollacSalviniadPteris
  40. A restriction endonuclease cuts a DNA moleculeaat random positions along the moleculebonly at the two ends of the moleculecat specific palindromic base sequencesdin single-stranded regions only

Chemistry (questions 81–130)

  1. The number of atoms present in 0.5 mol of helium gas isa6.02 × 10²³b1.5 × 10²³c1.2 × 10²⁴d3.01 × 10²³
  2. A compound contains 40.0% carbon, 6.7% hydrogen and 53.3% oxygen. Its empirical formula isaCH₂ObCHOcC₂H₄O₂dCH₄O
  3. The wavelength of a red photon is 620 nm. Taking hc = 1240 eV·nm, the energy of the photon isa1.0 eVb6.2 eVc2.0 eVd0.5 eV
  4. After the 4s orbital, the next orbital to be filled is thea4pb4dc3pd3d
  5. The most electronegative element in the periodic table isafluorineboxygencchlorinednitrogen
  6. Which of the following molecules is linear?aH₂ObCO₂cSO₂dNH₃
  7. The bond order of the oxygen molecule (O₂) isa1b1.5c2d3
  8. The oxidation state of oxygen in hydrogen peroxide (H₂O₂) isa−2b0c+1d−1
  9. The volume occupied by one mole of an ideal gas at STP isa22.4 Lb24.0 Lc11.2 Ld44.8 L
  10. A gas occupies 2 L at 300 K. At constant pressure, its volume at 600 K will bea1 Lb4 Lc2 Ld6 L
  11. The pH of a 0.01 M solution of sodium hydroxide isa2b12c10d4
  12. When sodium acetate is added to acetic acid solution, the ionisation of the acid isaincreasedbunaffectedcsuppresseddreversed
  13. Which of the following is a primary standard for volumetric analysis?aSodium hydroxidebAnhydrous sodium carbonatecHydrochloric aciddPotassium permanganate
  14. The rate constant of a first-order reaction is 0.693 min⁻¹. The half-life of the reaction isa0.693 minb6.93 minc10 mind1.0 min
  15. For the Daniell cell with E°cell = 1.10 V transferring 2 mol of electrons (F = 96,500 C/mol), the standard free-energy change ΔG° = −nFE° is abouta−106 kJ/molb−212 kJ/molc+212 kJ/mold−21.2 kJ/mol
  16. A negative value of the free-energy change (ΔG) for a reaction indicates that the reaction isaimpossiblebat equilibriumcspontaneousdendothermic
  17. The uranium isotope ²³⁸U has atomic number 92. The number of neutrons in its nucleus isa238b92c146d330
  18. Aqua regia, which dissolves gold, is a mixture of concentrated HCl and concentrated HNO₃ in the ratioa3 : 1b1 : 3c1 : 1d2 : 1
  19. Oxygen gas is prepared in the laboratory by heatingapotassium chloratebcalcium carbonatecsodium nitritedzinc granules
  20. The allotrope of phosphorus that is stored under water isared phosphorusbwhite phosphoruscblack phosphorusdviolet phosphorus
  21. The noble gases are chemically inert mainly because they haveaan unusually large atomic sizebvery low boiling and melting pointsconly paired electrons in s orbitalsda complete, stable outer electronic configuration
  22. Bauxite is the principal ore ofaironbcopperczincdaluminium
  23. Mercury is extracted from its ore calledagalenabcinnabarchaematitedmagnetite
  24. Brass is an alloy of copper withatinbzinccnickeldchromium
  25. Calcination is the process of heating a concentrated oreain a large excess of free airbtogether with coke as a reducing agentcin the absence (or limited supply) of airdwhile suspended in a stream of water
  26. The metal atom at the centre of the chlorophyll molecule isamagnesiumbironcmanganesedcopper
  27. Excess fluoride in drinking water leads to the disease calledaanaemiabfluorosiscgoitrednight blindness
  28. The inductive effect in a molecule is theapermanent polarisation of a sigma bondbtemporary displacement of π electronscdelocalisation over a conjugated systemdformation of hydrogen bonds
  29. Ethanol and dimethyl ether (both C₂H₆O) are a pair ofafunctional group isomersbchain isomerscposition isomersdstereoisomers
  30. The most stable carbocation among the following is theamethyl cationbprimary carbocationcsecondary carbocationdtertiary carbocation
  31. Chlorination of methane in sunlight proceeds by the mechanism ofaelectrophilic additionbnucleophilic substitutioncfree radical substitutiondelimination
  32. Baeyer's reagent, used to test for unsaturation, isaacidic KMnO₄bcold dilute alkaline KMnO₄cK₂Cr₂O₇ in aciddFehling's solution
  33. Benzene reacts with CH₃Cl in the presence of anhydrous AlCl₃ (Friedel–Crafts) to giveachlorobenzenebbenzyl chloridectoluenedxylene
  34. Ethanol heated with concentrated sulphuric acid at 443 K (170 °C) gives mainlyadiethyl etherbethanoic acidcethenedethyl hydrogen sulphate
  35. Phenol with bromine water gives a white precipitate ofa2,4,6-tribromophenolbbromobenzenecpicric aciddo-bromophenol
  36. Reactivity towards the S_N1 mechanism is highest for aamethyl halidebprimary alkyl halidecsecondary alkyl halidedtertiary alkyl halide
  37. Ethanol reacts with sodium metal to liberate the gasaoxygenbhydrogenccarbon dioxidedmethane
  38. The Cannizzaro reaction is shown by aldehydes that haveano α-hydrogen atombtwo α-hydrogen atomsca β-hydrogen atomda long carbon chain
  39. Fehling's solution is reduced (giving a red precipitate) byaketonesbaldehydescalcoholsdethers
  40. Acetic acid reacts with ethanol in the presence of an acid catalyst to formaan etherban anhydridecan alkenedan ester (ethyl acetate)
  41. Which carboxylic acid gives a silver mirror with Tollens reagent?aAcetic acidbPropanoic acidcBenzoic aciddFormic acid
  42. The Gabriel phthalimide synthesis is used for preparingaprimary aminesbsecondary aminesctertiary aminesdamides
  43. Benzene diazonium chloride couples with alkaline phenol to giveaan orange azo dyebbenzenecanilinedchlorobenzene
  44. Electrophilic substitution in nitrobenzene gives mainly theaortho productbpara productcmeta productddisubstituted product
  45. Bakelite is a polymer formed from phenol andaethenebchloroethenecstyrenedformaldehyde
  46. Milk of magnesia, used as an antacid, is a suspension ofaMgObMgCO₃cMgCl₂dMg(OH)₂
  47. The percentage of nitrogen by mass in urea, CO(NH₂)₂ (molar mass 60), is abouta21%b35%c47%d60%
  48. In chromatography, the R_f value of a component is defined as the distance moved by theasolvent divided by the distance moved by the componentbcomponent divided by the distance moved by the solvent frontccomponent multiplied by the solventdpaper divided by the solvent
  49. Unsaturation in an organic compound is indicated when it decolourisesaFehling's solutionbTollens reagentcbromine waterdLucas reagent
  50. In Kjeldahl's method of estimating nitrogen, the nitrogen of the compound is converted intoaammonium sulphatebnitrogen gascsodium cyanidedsodium nitrate

Physics (questions 131–180)

  1. A ball is thrown vertically upward with a speed of 20 m/s. The maximum height it reaches (g = 10 m/s²) isa10 mb20 mc40 md25 m
  2. The dimensional formula of momentum isa[MLT⁻¹]b[ML²T⁻²]c[MLT⁻²]d[ML²T⁻¹]
  3. A force of 50 N moves a body through 4 m in its own direction. The work done isa12.5 Jb200 Jc54 Jd400 J
  4. The kinetic energy of a 2 kg mass moving at 5 m/s isa10 Jb25 Jc50 Jd20 J
  5. A uniform disc of mass 4 kg and radius 0.2 m rotates about an axis through its centre perpendicular to its face. Its moment of inertia (½MR² for a disc) isa0.16 kg m²b0.04 kg m²c0.08 kg m²d0.8 kg m²
  6. Bernoulli's theorem for fluid flow is based on the conservation ofamassbmomentumcchargedenergy
  7. A particle executes SHM with amplitude 0.05 m and angular frequency 10 rad/s. The maximum acceleration of the particle isa0.5 m/s²b50 m/s²c5 m/s²d0.05 m/s²
  8. The angular velocity of the second hand of a clock isaπ/60 rad/sbπ/30 rad/sc2π rad/sdπ/15 rad/s
  9. Estimate the escape velocity from Earth using v = √(2gR) with g = 10 m/s² and R = 6.4 × 10⁶ m. The value obtained is abouta7.9 km/sb9.8 km/sc22.4 km/sd11.2 km/s
  10. Steel is more elastic than rubber because, for the same strain, steel developsaa much larger restoring stressba larger extensionca permanent setda smaller stress
  11. The handles of cooking vessels are made of wood or ebonite because these materials areagood conductors of heatbpoor conductors of heatcvery heavydeasily melted
  12. Heat from the Sun reaches the Earth mainly byaconductionbconvectioncradiationdconduction and convection
  13. In very cold countries the surface of a lake freezes, yet fish survive in the water below the ice. This is mainly becauseawater is densest at 4 °C and keeps the bottom unfrozenbice is a good conductor of heat to the watercfish produce antifreeze in large amountsdthe ice layer is only a few millimetres thick
  14. The heat needed to melt 0.5 kg of ice at 0 °C (latent heat of fusion = 3.34 × 10⁵ J/kg) isa1.67 × 10⁵ Jb3.34 × 10⁵ Jc6.68 × 10⁵ Jd8.35 × 10⁴ J
  15. A fixed mass of gas in a sealed rigid vessel is at 1.0 atm pressure and 27 °C. When it is heated to 127 °C, its pressure becomes abouta1.0 atmb2.0 atmc4.7 atmd1.33 atm
  16. A gas expands adiabatically and does 500 J of work on its surroundings. The change in its internal energy isa+500 Jbzeroc+1000 Jd−500 J
  17. In an isothermal change of an ideal gas, the quantity that remains unchanged is theawork donebinternal energycheat exchangeddpressure
  18. A closed organ pipe of length 25 cm produces a fundamental note of (velocity of sound = 340 m/s)a170 Hzb340 Hzc680 Hzd85 Hz
  19. The loudness level of a sound is measured inawattsbjoulescdecibelsdhertz
  20. In a stationary wave, the distance between two consecutive nodes isaλbλ/4c2λdλ/2
  21. A dentist holds a concave mirror of focal length 3 cm at a distance of 2 cm from a tooth. The magnification of the image seen isa3 times, erectb1/3, erectc2 times, invertedd6 times, inverted
  22. The image formed by a plane mirror is alwaysavirtual, erect and of the same sizebreal, inverted and of the same sizecvirtual, inverted and magnifieddreal, erect and diminished
  23. A ray passes through a thin prism of angle 6° made of glass of refractive index 1.5. The angle of deviation produced ((μ − 1)A for a thin prism) isa6°b9°c1.5°d3°
  24. For sustained interference of light, the two sources must essentially beavery strongbwidely separatedccoherentdpolarised
  25. The phenomenon of polarisation of light proves that light waves areatransverseblongitudinalcstationarydmechanical
  26. Kirchhoff's junction rule (ΣI = 0) is based on the conservation ofachargebenergycmomentumdmass
  27. Resistors of 2 Ω and 4 Ω in series are connected to a 12 V battery. The current in the circuit isa1 Ab2 Ac3 Ad6 A
  28. The wire used for an electric fuse should have aahigh melting pointblow melting pointcvery large thicknessdmelting point above copper
  29. An electron (charge 1.6 × 10⁻¹⁹ C) moves at 10⁷ m/s perpendicular to a magnetic field of 0.1 T. The force on it isa1.6 × 10⁻¹⁹ Nb1.6 × 10⁻⁷ Nc1.6 × 10⁻¹³ Nd1.6 × 10⁻¹² N
  30. A uniform magnetic field of 0.2 T is directed perpendicular to a flat coil of area 0.05 m². The magnetic flux through the coil isa0.01 Wbb4 Wbc0.25 Wbd0.001 Wb
  31. An example of a paramagnetic substance isabismuthbaluminiumccopperdwater
  32. A transformer steps 220 V down to 11 V. If its primary coil has 2000 turns, the number of turns in the secondary is (ideal transformer)a40,000b1000c200d100
  33. At resonance in a series LCR circuit, the current isamaximumbminimumczerodindependent of resistance
  34. A step-up transformer increases the alternatingavoltagebcurrentcpowerdfrequency
  35. The electric potential at a distance of 0.3 m from a point charge of 2 μC is abouta6 × 10³ Vb6 × 10⁶ Vc6 × 10⁴ Vd600 V
  36. The electric field inside a hollow charged conductor isamaximum at the centrebhalf the surface valuecinfinitedzero
  37. The energy stored in a 10 μF capacitor charged to 100 V isa0.5 Jb0.05 Jc5 Jd0.005 J
  38. A dielectric of constant K = 5 completely fills the space between the plates of a capacitor of capacitance C. The new capacitance isaC/5bCc5Cd25C
  39. In the photoelectric effect, the stopping potential depends on theaintensity of lightbdistance of the sourcecarea of the cathodedfrequency of the incident light
  40. The Compton effect provides evidence for theawave nature of light onlybcharge of the photoncparticle (momentum) nature of lightdmass of the photon at rest
  41. An electron gains 2 electron-volts (eV) of energy. In joules this energy is (1 eV = 1.6 × 10⁻¹⁹ J)a1.6 × 10⁻¹⁹ Jb3.2 × 10⁻¹⁸ Jc2.0 Jd3.2 × 10⁻¹⁹ J
  42. The Balmer series of the hydrogen spectrum lies in theaultraviolet regionbinfrared regioncvisible regiondX-ray region
  43. In the Bohr model the radius of the n-th orbit is proportional to n². The ratio of the radius of the third orbit to that of the first orbit isa3b9c27d6
  44. Isotopes of an element have the sameamass numberbnumber of neutronscatomic massdatomic number
  45. Gamma rays emitted by a nucleus areastreams of electronsbhelium nucleicelectromagnetic radiationdstreams of protons
  46. The material commonly used as a moderator in a nuclear reactor isaheavy waterbcadmiumcuranium-238dboron steel
  47. A p–n junction diode is most commonly used in circuits as aaamplifierboscillatorcmodulatordrectifier
  48. The output of an AND gate is 1 only whenaboth inputs are 1bat least one input is 1cboth inputs are 0dthe inputs are different
  49. The antiparticle of the electron is theaprotonbpositroncneutrinodphoton
  50. Hubble's law relates the recession velocity of a galaxy to itsasizebmasscdistance from usdtemperature

Mental Agility Test (questions 181–200)

  1. Choose the word nearest in meaning to RELUCTANT.aUnwillingbEagercReadydPleased
  2. Choose the word most opposite in meaning to ANCIENT.aOldbAntiquecHistoricaldModern
  3. Painter : Canvas :: Sculptor : ?aPaintbBrushcMarbledPicture
  4. Find the odd one out.aRosebLotuscJasminedLeaf
  5. A person who can use both hands equally well is calledaversatilebambivertcambidextrousdbilingual
  6. Find the next number in the series: 1, 4, 9, 16, 25, ?a30b36c49d35
  7. An article marked at Rs 500 is sold at a 20% discount. The selling price isaRs 400bRs 420cRs 480dRs 380
  8. The simple interest on Rs 1000 at 10% per annum for 2 years isaRs 100bRs 110cRs 120dRs 200
  9. Rs 50 is divided between two people in the ratio 2 : 3. The larger share isaRs 20bRs 30cRs 25dRs 35
  10. If x + 5 = 12, then 2x equalsa7b12c14d24
  11. Statements: All pens are books. All books are chairs. Which conclusion certainly follows?aAll chairs are pensbSome books are not penscAll pens are chairsdNo pen is a chair
  12. In a code, PEN is written as 35 (adding letter positions). In the same code, INK isa33b34c35d36
  13. A father is three times as old as his son. Their ages add up to 48 years. The son isa12 years oldb16 years oldc14 years oldd18 years old
  14. Find the next letter in the series: Z, X, V, T, ?aSbRcQdP
  15. Statement: Only students may enter the library. Ram entered the library. It follows thataRam is a studentbRam likes bookscRam is a teacherdall students are in the library
  16. How many squares are there in a 2 × 2 grid of small squares (counting squares of all sizes)?a4b6c9d5
  17. Which capital letter looks the same in its water image (reflection in a horizontal mirror)?aFbGcPdC
  18. Facing north, you turn right, then right again, then left. Which direction do you now face?aNorthbSouthcEastdWest
  19. On a die, 1 is opposite 6 and 2 is opposite 5. The face opposite 3 isa6b4c5d2
  20. A sheet of paper is folded once in half and two holes are punched through the folded sheet. On unfolding fully, the number of holes isa4b2c3d8

Answer key and explanations

Answers — Zoology (1–40)

1. (d) — One ancestral finch radiated into many beak forms for different niches.

2. (a) — The appendix is a reduced remnant of a once-functional caecum.

3. (a) — Lamarck proposed that acquired characters are inherited.

4. (b) — Cnidoblasts hold the stinging nematocysts of coelenterates.

5. (a) — The pearl oyster Pinctada secretes nacre around an irritant.

6. (c) — The sea horse is a true bony fish; the others are not fish at all.

7. (b) — The platypus is a monotreme that lays eggs yet suckles its young.

8. (d) — Tendons join muscle to bone (ligaments join bone to bone).

9. (c) — Osteocytes are the mature cells embedded in bone matrix.

10. (c) — Many-layered squamous epithelium protects the skin surface.

11. (d) — The epidermis is epithelial tissue, not connective tissue.

12. (a) — Ross showed the female Anopheles carries Plasmodium between hosts.

13. (d) — The young trophozoite inside a red blood cell looks like a signet ring.

14. (b) — The typhlosole is an intestinal fold that enlarges the absorbing area.

15. (a) — Gases exchange across the thin, moist body surface.

16. (c) — Sperms pass through the kidney via Bidder's canal to the urinogenital duct.

17. (c) — Only male frogs have vocal sacs, used in breeding calls.

18. (d) — Pepsin works in the strongly acidic gastric juice, pH about 1.5–2.

19. (b) — The small intestine's villi and microvilli absorb the digested food.

20. (b) — The residual volume (about 1.2 L) never leaves the lungs.

21. (a) — About 97% of oxygen travels bound to haemoglobin as oxyhaemoglobin.

22. (a) — Closure of the AV (mitral and tricuspid) valves makes the first sound.

23. (c) — The aorta is the largest artery, leaving the left ventricle.

24. (b) — Platelets plug injuries and help convert fibrinogen to fibrin.

25. (d) — The liver's urea cycle detoxifies ammonia into urea.

26. (b) — High capillary hydrostatic pressure filters plasma into Bowman's capsule.

27. (c) — The medulla houses the respiratory and cardiac control centres.

28. (d) — Hair cells of the organ of Corti sit on the basilar membrane of the cochlea.

29. (c) — Lack of insulin (or its action) raises blood glucose: diabetes mellitus.

30. (a) — The pituitary's trophic hormones direct most other endocrine glands.

31. (d) — The ovum is fertilised in the ampulla of the fallopian tube.

32. (b) — Progesterone from the corpus luteum maintains the endometrium.

33. (d) — HIV destroys CD4 helper T cells, collapsing cell-mediated immunity.

34. (d) — Rabies virus in saliva enters through the bite of an infected dog.

35. (b) — In active immunity the person's own immune system makes the antibodies.

36. (a) — The day-biting Aedes aegypti spreads dengue (and chikungunya, Zika).

37. (c) — CT combines many X-ray projections into cross-sectional images.

38. (a) — Dialysis does the filtering work of failed kidneys.

39. (b) — Chitwan (1973) was Nepal's first national park.

40. (c) — CO₂ from fossil fuels and deforestation dominates the added greenhouse effect.

Answers — Botany (41–80)

41. (a) — Peptide (amide) bonds link amino acids into a polypeptide.

42. (c) — Fat gives about 9.3 kcal/g, over twice the value of carbohydrate.

43. (c) — TMV is an RNA virus: a single RNA strand inside a protein rod.

44. (d) — A bacteriophage carries the genes between bacteria in transduction.

45. (d) — Fleming's penicillin came from Penicillium notatum.

46. (b) — Lichens die back where SO₂ pollutes the air, marking clean-air zones.

47. (b) — Diatom frustules are glassy silica boxes.

48. (d) — Their swimming sperms need a film of water to reach the archegonium.

49. (a) — Selaginella makes microspores and megaspores: heterospory.

50. (d) — Coralloid roots of Cycas house nitrogen-fixing cyanobacteria.

51. (c) — The mint family (Lamiaceae) has square stems and two-lipped flowers.

52. (a) — Secondary succession rebuilds on soil where a community was disturbed.

53. (a) — Interlocking feeding links buffer the ecosystem against one species' loss.

54. (c) — Nutrient runoff of nitrates/phosphates triggers algal blooms and deoxygenation.

55. (a) — Pneumatophores rise above the mud to take in air for the roots.

56. (b) — Their acid hydrolases can digest the cell itself if released.

57. (b) — At metaphase the chromosomes line up on the equator.

58. (a) — Chiasmata form as chromatids exchange parts during pachytene.

59. (b) — Ribosomal RNA is transcribed and pre-ribosomes assembled in the nucleolus.

60. (b) — Ribosome-studded rough ER folds and processes proteins for export.

61. (c) — Independent assortment gives 9:3:3:1 in a dihybrid F₂.

62. (a) — One gene, three alleles (Iᴬ, Iᴮ, i): multiple allelism (with codominance in AB).

63. (d) — B-DNA has about 10 base pairs (10.5) per 3.4 nm turn.

64. (a) — A = T = 20%, leaving 60% for G + C, so G = 30%.

65. (a) — RNA polymerase reads the template strand to build the RNA.

66. (b) — The third ("wobble") position tolerates loose pairing with the anticodon.

67. (a) — The cork cambium (phellogen) cuts off cork outward.

68. (b) — Wide vessel elements are the main water pipes of angiosperms.

69. (c) — Root xylem and phloem lie on alternate radii: radial bundles.

70. (c) — Dixon and Joly (1894) proposed transpiration-pull cohesion–tension.

71. (d) — K⁺ uptake makes guard cells turgid so the pore opens.

72. (d) — Isotope experiments show the evolved O₂ comes from split water.

73. (c) — Krebs-cycle enzymes (except one) work in the mitochondrial matrix.

74. (d) — Alcoholic fermentation: glucose → 2 ethanol + 2 CO₂.

75. (d) — Abscisic acid enforces dormancy and shuts stomata in water stress.

76. (b) — The pollen grain is the highly reduced male gametophyte.

77. (c) — Seven cells but eight nuclei (the central cell holds two polar nuclei).

78. (d) — Inserted genes make the grain accumulate provitamin A.

79. (b) — Azolla with its Anabaena partner fixes N for the paddy crop.

80. (c) — Restriction enzymes recognise short palindromic sites and cut there.

Answers — Chemistry (81–130)

81. (d) — 0.5 × 6.02 × 10²³ = 3.01 × 10²³ atoms.

82. (a) — Mole ratio C : H : O = 3.33 : 6.7 : 3.33 = 1 : 2 : 1 → CH₂O.

83. (c) — E = hc/λ = 1240/620 = 2.0 eV: energy is inversely proportional to wavelength.

84. (d) — By the (n + l) rule, 3d follows 4s.

85. (a) — Fluorine tops the Pauling electronegativity scale.

86. (b) — O=C=O is linear; H₂O and SO₂ are bent, NH₃ pyramidal.

87. (c) — Molecular-orbital theory gives O₂ a bond order of 2.

88. (d) — In peroxides oxygen has the unusual oxidation state −1.

89. (a) — Molar volume at STP is 22.4 L.

90. (b) — Charles's law: V ∝ T, so doubling T (K) doubles V to 4 L.

91. (b) — pOH = 2, hence pH = 14 − 2 = 12.

92. (c) — The common acetate ion pushes the acid's equilibrium back (common-ion effect).

93. (b) — Anhydrous Na₂CO₃ is stable and pure; NaOH and KMnO₄ are not primary standards.

94. (d) — t½ = 0.693/k = 0.693/0.693 = 1.0 min, independent of the starting concentration (first order).

95. (b) — ΔG° = −2 × 96,500 × 1.10 ≈ −212 kJ/mol; the negative sign matches a spontaneous cell reaction (the SHE is the 0.00 V reference for such potentials).

96. (c) — ΔG negative means the process is spontaneous.

97. (c) — Neutrons = mass number − atomic number = 238 − 92 = 146 (β⁻ decay converts one of them into a proton, raising Z by 1).

98. (a) — Aqua regia = 3 parts conc. HCl to 1 part conc. HNO₃.

99. (a) — 2KClO₃ → 2KCl + 3O₂ on heating (MnO₂ catalyst).

100. (b) — White phosphorus ignites in air, so it is kept under water.

101. (d) — A filled octet (duplet for He) makes electron gain/loss unfavourable.

102. (d) — Bauxite (Al₂O₃·2H₂O) is aluminium's main ore.

103. (b) — Cinnabar (HgS) is roasted to give mercury.

104. (b) — Brass = copper + zinc (bronze = copper + tin).

105. (c) — Calcination heats the ore without air to drive off volatiles.

106. (a) — Mg²⁺ sits at the centre of the chlorophyll ring.

107. (b) — Chronic excess fluoride mottles teeth and stiffens joints: fluorosis.

108. (a) — The inductive effect is permanent σ-bond polarisation toward an electronegative group.

109. (a) — Same formula, different functional group (–OH vs –O–).

110. (d) — Alkyl groups stabilise a carbocation; tertiary is the most stable.

111. (c) — Sunlight splits Cl₂ into radicals that substitute H of methane.

112. (b) — Cold, dilute, alkaline KMnO₄ is Baeyer's reagent for C=C/C≡C.

113. (c) — Friedel–Crafts methylation of benzene gives toluene.

114. (c) — At 170 °C ethanol dehydrates to ethene (ether forms at 140 °C).

115. (a) — The activated ring is tribrominated to white 2,4,6-tribromophenol.

116. (d) — S_N1 goes through a carbocation, so tertiary halides react fastest.

117. (b) — 2C₂H₅OH + 2Na → 2C₂H₅ONa + H₂.

118. (a) — Aldehydes without α-H (e.g. HCHO) self-oxidise and reduce in conc. alkali.

119. (b) — Aldehydes reduce Fehling's Cu²⁺ to red Cu₂O.

120. (d) — Esterification gives ethyl acetate and water.

121. (d) — Formic acid has an aldehyde-like H–C=O group and reduces Tollens' reagent.

122. (a) — Gabriel synthesis yields pure primary amines.

123. (a) — Azo coupling gives the orange dye p-hydroxyazobenzene.

124. (c) — The –NO₂ group is strongly deactivating and meta-directing.

125. (d) — Phenol + formaldehyde polymerise to the thermoset Bakelite.

126. (d) — Milk of magnesia is aqueous Mg(OH)₂.

127. (c) — Two nitrogen atoms contribute 28 of the 60 g/mol: 28/60 ≈ 47% — the highest among common nitrogenous fertilisers.

128. (b) — R_f = distance moved by component ÷ distance moved by solvent front.

129. (c) — A C=C or C≡C bond quickly absorbs Br₂, discharging its colour.

130. (a) — Digestion with conc. H₂SO₄ converts the nitrogen to (NH₄)₂SO₄.

Answers — Physics (131–180)

131. (b) — h = u²/2g = 400/20 = 20 m.

132. (a) — p = mv gives [MLT⁻¹].

133. (b) — W = Fs = 50 × 4 = 200 J.

134. (b) — KE = ½mv² = ½ × 2 × 25 = 25 J.

135. (c) — I = ½ × 4 × (0.2)² = 0.08 kg m² (half that of a ring of the same mass and radius).

136. (d) — Bernoulli's equation is energy conservation per unit volume.

137. (c) — amax = ω²A = 100 × 0.05 = 5 m/s², occurring at the extreme positions.

138. (b) — ω = 2π/60 = π/30 rad/s.

139. (d) — √(2 × 10 × 6.4 × 10⁶) ≈ 11,300 m/s ≈ 11.2 km/s (not dependent on the projectile's mass).

140. (a) — Steel's Young modulus is huge: small strain, large stress — hence "more elastic".

141. (b) — Wood and ebonite insulate the hand from the hot vessel.

142. (c) — Radiation needs no medium and crosses the vacuum from the Sun.

143. (a) — Water contracts on cooling only down to 4 °C; the densest (4 °C) water sinks and stays liquid beneath the insulating ice — the anomalous expansion of water.

144. (a) — Q = mL = 0.5 × 3.34 × 10⁵ = 1.67 × 10⁵ J.

145. (d) — At constant volume P ∝ T (kelvin): P = 1.0 × 400/300 = 1.33 atm. Using Celsius degrees directly (127/27) is the trap.

146. (d) — Adiabatic means ΔQ = 0, so ΔU = −W = −500 J: the work is paid for out of internal energy, and the gas cools.

147. (b) — For an ideal gas, U depends only on T, which is constant.

148. (b) — f = v/4L = 340/(4 × 0.25) = 340 Hz for a closed pipe.

149. (c) — Loudness level is quoted in decibels.

150. (d) — Successive nodes (and antinodes) are λ/2 apart.

151. (a) — Inside the focal length, 1/v = 1/3 − 1/2 < 0 gives a virtual image with m = f/(f − u) = 3: erect and three times enlarged.

152. (a) — Plane mirrors give virtual, erect, same-size images.

153. (d) — δ = (1.5 − 1) × 6° = 3°, towards the base of the prism (violet deviates a little more than red).

154. (c) — Coherent sources keep a constant phase difference.

155. (a) — Only transverse waves can be polarised.

156. (a) — Currents balance at a junction because charge is conserved.

157. (b) — I = V/R = 12/(2 + 4) = 2 A.

158. (b) — A fuse wire melts quickly (low melting point) when current is excessive.

159. (c) — F = qvB = 1.6 × 10⁻¹⁹ × 10⁷ × 0.1 = 1.6 × 10⁻¹³ N.

160. (a) — Φ = BA = 0.2 × 0.05 = 0.01 Wb (weber). Tilting the coil would multiply this by cosθ.

161. (b) — Aluminium is paramagnetic; bismuth, copper and water are diamagnetic.

162. (d) — Ns/Np = Vs/Vp = 11/220 = 1/20, so Ns = 100 turns (mutual induction sets the turns ratio).

163. (a) — Impedance is minimum (= R) at resonance, so current is maximum.

164. (a) — A step-up transformer raises voltage (and lowers current).

165. (c) — V = 9 × 10⁹ × 2 × 10⁻⁶/0.3 = 6 × 10⁴ V.

166. (d) — Electrostatic shielding: the field inside a hollow conductor is zero.

167. (b) — U = ½CV² = ½ × 10 × 10⁻⁶ × 10⁴ = 0.05 J.

168. (c) — Full dielectric multiplies capacitance by K: 5C.

169. (d) — Stopping potential measures maximum KE, set by frequency (Einstein equation).

170. (c) — Compton scattering treats the photon as a particle carrying momentum.

171. (d) — 2 × 1.6 × 10⁻¹⁹ = 3.2 × 10⁻¹⁹ J: the eV is a tiny, atom-sized unit of energy.

172. (c) — Balmer lines (transitions to n = 2) fall in visible light.

173. (b) — r₃/r₁ = 3²/1² = 9.

174. (d) — Isotopes share Z (protons) but differ in neutrons.

175. (c) — γ rays are high-energy photons, uncharged electromagnetic radiation.

176. (a) — Heavy water (or graphite) slows neutrons; cadmium/boron absorb them in control rods.

177. (d) — One-way conduction makes the diode a rectifier of a.c.

178. (a) — AND needs both inputs high for a high output.

179. (b) — The positron is the electron's antiparticle.

180. (c) — v = H₀d: recession speed grows with distance.

Answers — Mental Agility Test (181–200)

181. (a) — Reluctant means unwilling or hesitant.

182. (d) — Modern is the opposite of ancient.

183. (c) — A painter works on canvas; a sculptor works on marble (stone).

184. (d) — Rose, lotus and jasmine are flowers; a leaf is not.

185. (c) — Ambidextrous = equally able with both hands.

186. (b) — Squares: 1², 2², 3², 4², 5², so next is 6² = 36.

187. (a) — 500 − 20% of 500 = 500 − 100 = Rs 400.

188. (d) — SI = 1000 × 10 × 2/100 = Rs 200.

189. (b) — Larger share = 3/5 × 50 = Rs 30.

190. (c) — x = 7, so 2x = 14.

191. (c) — Pens ⊆ books ⊆ chairs, so all pens are chairs.

192. (b) — I + N + K = 9 + 14 + 11 = 34 (PEN = 16 + 5 + 14 = 35).

193. (a) — Son = 48/4 = 12; father = 36.

194. (b) — Step back two letters each time: Z, X, V, T, R.

195. (a) — Entry is restricted to students, so Ram must be one.

196. (d) — Four small squares plus the one big square = 5.

197. (d) — C has horizontal symmetry, so its water image is itself.

198. (c) — North → east → south → east.

199. (b) — The remaining pair of faces is 3 and 4.

200. (a) — One fold gives 2 layers; two punched holes become 4 on unfolding.