Model Paper 4

Chapter 5 · Full Model Papers · 200 questions in the paper · 37 min read

Model Paper 4

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. The modern synthetic theory of evolution combines natural selection withaLamarckismbspecial creationcinheritance of acquired charactersdMendelian genetics and mutation
  2. The book On the Origin of Species (1859), presenting the theory of natural selection, was written byaLamarckbAlfred Russel Wallace alonecGregor MendeldCharles Darwin
  3. Speciation that occurs when populations are separated by a geographical barrier is calledasympatric speciationballopatric speciationcparthenogenesisdhybridisation
  4. The hard exoskeleton of arthropods is made ofacellulosebchitinckeratindsilica
  5. Octopus belongs to the phylumaMolluscabArthropodacEchinodermatadCnidaria
  6. The water vascular (ambulacral) system used in locomotion is found in theaearthwormbgarden snailcspiderdstarfish
  7. In a fish, blood pumped by the heart passes through the gills before reaching the rest of the body (single circulation). A direct consequence of this arrangement is thatablood reaches the body tissues at relatively low pressureboxygenated and deoxygenated blood mix freely in the heartcthe heart must have four chambersdthe body receives blood faster than in mammals
  8. Heparin and histamine are secreted by the connective-tissue cells calledaplasma cellsbfibroblastscmast cellsdadipocytes
  9. The organic (protein) matrix of bone consists mainly ofacollagen (ossein)bkeratincelastin onlydactin
  10. The cilia of the epithelium lining the trachea serve toaabsorb oxygen from the inhaled airbsecrete digestive enzymes into the airwaycsweep mucus and dust particles outwarddvibrate the vocal cords to produce sound
  11. Fat is stored in the body mainly in the tissue calledaadipose tissuebareolar tissuectendondligament
  12. In Plasmodium, the gametes are formed from the gametocytes inside theahuman red blood cellsbhuman livercstomach of the mosquitodsalivary glands
  13. The recurrence (relapse) of vivax malaria is due to dormant hypnozoites lodged in theablood plasmabspleencbone marrowdliver
  14. The bristle-like setae of the earthworm principally help it inadigestionblocomotion and gripping the soilcrespirationdreproduction
  15. Food (soil organic matter) is ground up in the part of the earthworm gut called theatyphlosolebcropcpharynxdgizzard
  16. In the frog, the urinary bladder opens into theaureterbrectumccloacadexterior directly
  17. The red blood cells of the frog, unlike those of man, areaenucleated and biconcavebnucleated and ovalcabsent in adultsdidentical to white blood cells
  18. Bile, which helps in the digestion of fats, is produced by theaduodenumbpancreascspleendliver
  19. Salivary amylase (ptyalin) begins the digestion ofaproteinsbfatsccellulosedstarch
  20. The breathing rate is regulated mainly by chemoreceptors sensitive to the blood level ofaoxygen alonebcarbon dioxide (H⁺)cnitrogendglucose
  21. During inspiration, the diaphragmacontracts and flattens downwardbrelaxes and becomes dome-shapedcremains inactivedpushes the ribs inward
  22. The human heart is described as myogenic because the heartbeat originates in theamotor areas of the cerebral cortexbreflex centres of the spinal cordcmuscle of the heart itself (SA node)dcardiac centre of the medulla oblongata
  23. The valve between the left atrium and the left ventricle is theabicuspid (mitral) valvebtricuspid valvecsemilunar valvedEustachian valve
  24. The spleen is sometimes called the "graveyard of RBCs" because itaproduces bilebstores urinecdestroys worn-out red blood cellsdsecretes insulin
  25. Ultrafiltration of the blood in the kidney takes place in theaproximal tubulebloop of Henlecglomerulus and Bowman's capsuledcollecting duct
  26. Diabetes insipidus (production of large volumes of dilute urine) results from deficiency ofainsulinbADH (vasopressin)cglucagondparathormone
  27. In a simple reflex arc, the nerve impulse travels in the orderareceptor → sensory neuron → CNS → motor neuron → effectorbeffector → motor neuron → CNS → sensory neuroncmotor neuron → receptor → CNS → effectordCNS → receptor → effector → motor neuron
  28. Near and distant objects are focused on the retina by changing the shape of the lens through theaciliary musclesbirisccorneadoptic nerve
  29. The synthesis of thyroxine by the thyroid gland requires the elementaironbcalciumciodinedpotassium
  30. Insulin is secreted by which cells of the islets of Langerhans?aAlpha cellsbBeta cellscDelta cellsdAcinar cells
  31. The stage of the human embryo that implants in the uterine wall is theazygotebmorulacgastruladblastocyst
  32. Identical twins develop from a single fertilised egg and are calledamonozygotic twinsbdizygotic twinscfraternal twinsdSiamese twins only
  33. Elephantiasis (filariasis), with gross swelling of the limbs, is caused by the wormaWuchereria bancroftibTaenia soliumcFasciola hepaticadEnterobius
  34. Antibodies are manufactured and released by theaT-lymphocytes acting entirely on their ownbplasma cells (derived from B-lymphocytes)cmacrophages that engulf the pathogensdmature red blood cells of the circulation
  35. The first successful vaccination, against smallpox using cowpox material, was performed byaPasteurbRobert KochcJonas SalkdEdward Jenner
  36. Typhoid fever is caused by aavirusbbacteriumcprotozoandhelminth worm
  37. Ultrasonography (USG) produces images of internal organs by usingaX-raysbstrong magnetschigh-frequency sound wavesdgamma rays
  38. The ELISA test is commonly used as a screening test for infection byamalarial parasitesbblood sugar disorderscurinary infectionsdHIV
  39. On a steep, deforested hill slope in Nepal, the environmental problem that increases most directly when the tree cover is removed isathe height of the water table in wellsbthe amount of winter snowfallcsoil erosion and landslide risk during monsoon raindsalinity of the soil
  40. The Ramsar Convention is an international treaty for the conservation ofadesertsbwetlandscthe ozone layerdcoral reefs only

Botany (questions 41–80)

  1. Nucleic acids are polymers built from repeating units calledaamino acidsbnucleotidescmonosaccharidesdfatty acids
  2. Chemically, most enzymes are made ofaproteinsbcarbohydratesclipidsdvitamins
  3. The protein coat that encloses the nucleic acid of a virus is theacell wallbcapsuleccapsiddpellicle
  4. Rod-shaped bacteria are known asacoccibspirillacvibriosdbacilli
  5. The black bread mould commonly growing on stale bread isaRhizopusbPenicilliumcAspergillusdyeast
  6. In a mycorrhizal association, the fungus lives in close association with thealeaves of legumesbtrunk of treescroots of higher plantsdthallus of an alga
  7. The reserve food material stored in brown algae isastarchbglycogencfloridean starchdlaminarin (and mannitol)
  8. The green, filamentous juvenile stage in the life cycle of a moss is theaprotonemabthalluscprothallusdsporogonium
  9. The conspicuous leafy fern plant represents theasporophytebgametophytecprothallusdspore mother cell
  10. The xylem of typical gymnosperms differs from that of angiosperms in lackingatracheidsbparenchymacvesselsdfibres
  11. Tetradynamous stamens (four long and two short) are characteristic of the mustard family,aFabaceaebBrassicaceaecPoaceaedAsteraceae
  12. An ecosystem consists ofaonly the living organisms of an areabonly the non-living environmentconly the producers of the areadthe community plus its abiotic environment
  13. The final, stable community reached at the end of ecological succession is theapioneer communitybclimax communitycseredecotone
  14. The amount of living material present in a trophic level at a given time is theagross primary productivitybstanding cropcnet primary productivitydstanding state
  15. Sunken stomata in the leaves of desert plants serve toaincrease transpirationbabsorb dewcreduce loss of waterdtrap insects
  16. In the four-o'clock plant, offspring grown from seeds of a variegated (green-and-white) branch show the leaf colour of the mother branch, whatever the pollen parent. This is because the character is carried byagenes on the Y chromosome of the pollenbplastids inherited through the cytoplasm of the eggcdominant nuclear genes from the motherdmineral nutrients absorbed by the seed
  17. In plant cells, cytokinesis is accomplished by the formation of aacleavage furrowbconstriction ringcbuddcell plate
  18. In a flowering plant, meiosis leading to the megaspore occurs in theamale gamete inside the pollen grainbegg cell of the embryo saccmegaspore mother cell within the ovuledtriploid nucleus of the endosperm
  19. Peroxisomes of green leaves take part, together with chloroplasts and mitochondria, in the process ofaphotorespirationbphotosynthesis in the darkcnitrogen fixationdfermentation
  20. Plasmodesmata are the structures thataline the pits of xylem onlybare holes in the nuclear membranecconnect the cytoplasm of adjacent plant cellsdare gaps in the cell membrane
  21. Alleles are alternative forms of a gene occupying theasame locus on non-homologous chromosomesbdifferent loci on the same chromosomecwhole of a chromosomedsame locus on homologous chromosomes
  22. The human AB blood group, in which both A and B antigens are fully expressed, illustratesacodominancebincomplete dominancecsimple dominancedrecessiveness
  23. The two strands of a DNA double helix are antiparallel, which means that theyarun in the same 5′→3′ directionbrun in opposite directionsclie at right anglesdare joined end to end
  24. The enzyme that unwinds and separates the two strands of DNA during replication isaligasebprimasecDNA polymerase Idhelicase
  25. The genetic code is called degenerate becauseaone codon codes for many amino acidsbit has no punctuationcit is the same in all organismsdseveral codons may code for the same amino acid
  26. In the lac operon of E. coli, the substance that acts as the inducer isaglucoseblactose (allolactose)ctryptophandthe repressor protein
  27. The bulliform (motor) cells of grass leaves bring aboutaa faster rate of photosynthesis in the leafbinward rolling of the leaf in dry weathercmechanical support of the thin leaf bladedsecretion of nectar at the leaf margins
  28. The heartwood of a tree trunk is theainner, older, non-conducting xylembouter, younger, conducting xylemcinnermost layer of secondary phloemdstrip of actively dividing cambium
  29. Palisade mesophyll, the main photosynthetic tissue of a dicot leaf, liesatowards the lower epidermisbin the midrib onlycjust below the upper epidermisdin the petiole
  30. Water from the soil enters a root hair because the cell sap of the root hair has, compared with the soil solution, aaa higher water potential than the soil waterblower water potential (more concentrated sap)ca water potential exactly equal to that of soilda membrane that has become freely leaky
  31. The rate of transpiration from a cut shoot is commonly measured with aaauxanometerbrespirometercpotometerdphotometer
  32. The rate of photosynthesis is generally greatest in the region of visible light that isagreenbyellowcultravioletdred
  33. The net gain of ATP when one glucose molecule is fermented (anaerobic respiration) isa38 ATPb2 ATPc8 ATPdzero ATP
  34. The chemiosmotic theory of ATP synthesis was proposed byaPeter MitchellbHans KrebscMelvin CalvindRobert Emerson
  35. Ripening of fruits such as banana and mango is hastened by the gaseous hormoneaauxinbcytokinincethylenedabscisic acid
  36. A potato tuber is propagated vegetatively through its "eyes", which are the buds of a modifiedarootbleafcflowerdstem
  37. Light-sensitive lettuce seeds are induced to germinate by exposure toared lightbfar-red lightccomplete darknessdultraviolet light
  38. The first recombinant-DNA medicine to be marketed for human use (1982) wasaa hepatitis vaccinebhuman growth hormonecinterferondhuman insulin (Humulin)
  39. A crop commonly grown and ploughed into the field as green manure isaricebwheatcdhaincha (Sesbania)dmustard
  40. Cryopreservation of germplasm is carried out in liquid nitrogen at the temperature ofa−196 °Cb−20 °Cc0 °Cd−80 °C

Chemistry (questions 81–130)

  1. For the complete combustion CH₄ + 2O₂ → CO₂ + 2H₂O, the number of moles of oxygen needed to burn 2 mol of methane isa4b2c1d8
  2. The percentage by mass of hydrogen in water (H₂O) is abouta5.5%b88.9%c33.3%d11.1%
  3. An electron transition in an atom releases a photon of energy 2.55 eV (hc = 1240 eV·nm). The wavelength of the radiation emitted is abouta243 nmb486 nmc656 nmd972 nm
  4. The shape of an orbital is determined mainly by the quantum numberaprincipal (n)bmagnetic (m)cazimuthal (l)dspin (s)
  5. The smallest atomic radius among the following atoms is that ofasodiumbfluorinecchlorinedpotassium
  6. Diamond is extremely hard because its carbon atoms are joined inaan ionic lattice of positive and negative ionsbflat layers that slide easily over each otherca giant three-dimensional covalent networkda metallic lattice with free-moving electrons
  7. The most polar covalent bond among the following isaH–HbC–HcH–CldH–F
  8. In the reaction Zn + CuSO₄ → ZnSO₄ + Cu, zinc acts as a reducing agent because itagains electronsbgains hydrogencloses electronsdloses oxygen
  9. The vapour density of a gas is 22. Its molar mass isa44 g/molb22 g/molc11 g/mold88 g/mol
  10. The volume of 3 mol of an ideal gas at 300 K and 2 atm (R = 0.0821 L atm mol⁻¹ K⁻¹) is abouta12.3 Lb24.6 Lc36.9 Ld73.9 L
  11. At equilibrium for the reaction A ⇌ 2B, the concentrations are [A] = 0.5 mol/L and [B] = 1.0 mol/L. The equilibrium constant Kc = [B]²/[A] isa2b0.5c1d4
  12. A solution having pH 9 isastrongly acidicbweakly basic (alkaline)cexactly neutraldweakly acidic
  13. Methyl orange indicator shows in acidic solution the colourayellowbcolourlesscbluedred (pink)
  14. For a reaction, doubling the concentration of A (B kept constant) makes the rate four times, while doubling B (A kept constant) doubles the rate. The overall order of the reaction isa1b2c3d4
  15. Given standard reduction potentials E°(Cu²⁺/Cu) = +0.34 V and E°(Zn²⁺/Zn) = −0.76 V, the standard e.m.f. of the Daniell cell Zn | Zn²⁺ || Cu²⁺ | Cu isa0.42 Vb0.76 Vc1.10 Vd0.34 V
  16. The standard enthalpy of formation of an element in its standard state is taken asazerob100 kJ/molcalways positivedalways negative
  17. In the decay series from uranium-238 (mass number 238) to lead-206 (mass number 206), the number of alpha particles emitted is found from the mass numbers alone to bea4b6c16d8
  18. In the Haber process for the manufacture of ammonia, the catalyst used isaplatinumbiron (with promoters)cvanadium pentoxidednickel
  19. The Contact process, using V₂O₅ to oxidise SO₂ to SO₃, is used to manufactureaammoniabnitric acidchydrochloric aciddsulphuric acid
  20. The principal constituent of common glass and of sand isasilica (SiO₂)bsilicon carbidecelemental silicondsilicone oil
  21. Bleaching powder, used for disinfecting water, has the approximate formulaaCaCl₂bCa(OH)₂cCaCO₃dCaOCl₂
  22. Aluminium is extracted commercially by theareduction of its ore with coke in a furnacebelectrolysis of molten alumina dissolved in cryolitecfractional distillation of purified bauxitedstrong roasting of the mineral cryolite
  23. The thermite mixture used for welding railway tracks consists essentially ofaaluminium powder and ferric oxidebzinc and copper oxidecmagnesium and waterdcopper and sulphur
  24. Ordinary solder, used for joining metals, is an alloy ofacopper and zincbiron and chromiumczinc and tindlead and tin
  25. Roasting of an ore (for example a sulphide ore) means heating it stronglyain the absence of airbin watercin hydrogendin excess of air
  26. The conduction of nerve impulses in the body depends mainly on the movement of the ionsaCa²⁺ onlybFe²⁺ and Fe³⁺cNa⁺ and K⁺dZn²⁺ only
  27. A deficiency of iron in the human diet leads toaanaemiabgoitrecfluorosisddiabetes
  28. Two resonance (canonical) structures of a molecule differ from each other only in theapositions occupied by the individual atomsbtotal number of atoms present in the moleculecarrangement (distribution) of electronsdmolecular formula of the compound itself
  29. Geometrical (cis–trans) isomerism is possible in an alkene whenaevery bond in the molecule is a single bondbeach double-bonded carbon carries two different groupsca carbon–carbon triple bond is presentdthe molecule is ionic rather than covalent
  30. An example of a nucleophile (electron-pair donor) is theaBF₃ moleculebhydroxide ion, OH⁻cnitronium ion, NO₂⁺dAlCl₃ molecule
  31. Liquefied petroleum gas (LPG) used for cooking consists mainly ofamethane alonebhydrogen and carbon monoxidecacetylenedpropane and butane
  32. Ethene reacts with bromine in CCl₄ (decolourising it) to giveabromoetheneb1,2-dibromoethanecbromoethane and HBrdtetrabromoethane
  33. The actual electrophile that attacks the benzene ring during nitration is theaNO⁺ ionbNO₂ moleculecnitronium ion, NO₂⁺dHNO₃ molecule
  34. Chlorobenzene is much less reactive than alkyl chlorides towards nucleophilic substitution because resonance gives the C–Cl bondapartial double-bond characterba longer lengthcionic characterdfree rotation
  35. On strong oxidation with acidified K₂Cr₂O₇ and heating, ethanol is converted intoaethanoic acidbethanal onlycethenedcarbon monoxide only
  36. Diethyl ether must be stored carefully because on long exposure to air and light it forms explosiveaoxides of carbonbcarboxylic acidscperoxidesdaldehydes only
  37. Phenol is also known by the older name ofabenzoic acidbcarbolic acidcsalicylic aciddpicric acid
  38. Ethanal (acetaldehyde) with dilute sodium hydroxide undergoes the reaction calledaCannizzaro reactionbiodoform reaction onlycaldol condensationdesterification
  39. Which of the following compounds does NOT reduce Fehling's solution?aEthanalbGlucosecFormaldehydedAcetone (propanone)
  40. The alkaline hydrolysis of a fat or an ester to give soap is termedaesterificationbsaponificationchydrogenationdsulphonation
  41. The acid-dissociation constants at 25 °C are: HF 6.8 × 10⁻⁴, acetic acid 1.8 × 10⁻⁵, HCN 4.9 × 10⁻¹⁰, phenol 1.3 × 10⁻¹⁰. The strongest of these four acids isaHFbacetic acidcHCNdphenol
  42. Aniline treated with NaNO₂ and HCl at 0–5 °C (diazotisation) givesabenzene diazonium chloridebphenol directlycnitrobenzenedchlorobenzene
  43. The Hoffmann bromamide reaction converts a primary amide into aaa carboxylic acid with the same carbon skeletonbprimary amine with one carbon fewerca nitrile carrying the same number of carbonsda primary alcohol with one carbon more
  44. The explosive TNT is chemicallyanitroglycerinebpicric acidcdynamited2,4,6-trinitrotoluene
  45. The monomer from which PVC (polyvinyl chloride) is made isaethenebchloroethene (vinyl chloride)cstyrenedpropene
  46. The antibiotic penicillin was discovered (1928) byaEdward JennerbPasteurcPaul EhrlichdAlexander Fleming
  47. Muriate of potash, a common potassic fertiliser, isaKNO₃bK₂SO₄cKCldKOH
  48. A white precipitate, insoluble in dilute HCl, obtained with acidified BaCl₂ solution confirms the presence ofasulphate ionsbcarbonate ionscchloride ionsdnitrate ions
  49. Lead-acetate paper turning black is a test for the gasahydrogen sulphide (sulphide)bcarbon dioxidecammoniadchlorine
  50. In the Dumas method for estimating nitrogen in an organic compound, the nitrogen is finally obtained and measured asaammoniabfree nitrogen gas, N₂csodium cyanidedammonium nitrate

Physics (questions 131–180)

  1. A body travels 30 m due east and then 40 m due north. The magnitude of its net displacement from the starting point isa70 mb50 mc10 md35 m
  2. Which of the following quantities is a vector?aVelocitybSpeedcMassdTemperature
  3. A rifle of mass 4 kg fires a bullet of mass 20 g with a speed of 400 m/s. The recoil speed of the rifle isa0.2 m/sb2 m/sc20 m/sd1 m/s
  4. The work done by the centripetal force on a body in uniform circular motion over one complete revolution isazerobmv²cF × rd2πrF
  5. A flywheel has a moment of inertia of 2 kg m² about its axle and rotates at 10 rad/s. Its rotational kinetic energy isa10 Jb20 Jc100 Jd200 J
  6. In a hydraulic lift the area of the larger piston is 50 times that of the smaller piston. A force of 100 N applied to the small piston can support a load of up toa500 Nb5000 Nc50,000 Nd1000 N
  7. A mass on a spring (force constant 200 N/m) oscillates with amplitude 0.10 m. Its kinetic energy when the displacement is 0.05 m isa1.0 Jb0.25 Jc0.75 Jd0.50 J
  8. If a simple pendulum is taken to the Moon (where g is smaller), its time period willadecreasebremain the samecbecome zerodincrease
  9. The weight of a body at the centre of the Earth (assuming uniform density) isamaximumbinfiniteczerodhalf its surface weight
  10. A sample of rubber undergoes a volume strain of 0.5% when the pressure on it is increased by 1 × 10⁷ Pa. Its bulk modulus is abouta2 × 10⁸ Pab2 × 10⁹ Pac5 × 10⁸ Pad1 × 10¹⁰ Pa
  11. Heat transfer by convection can take place significantly inasolids onlyba vacuumcmetals onlydliquids and gases (fluids)
  12. A metal rod conducts heat at 10 J/s when the temperature difference between its ends is 50 °C. With the same rod, the rate of conduction when the difference is 25 °C isa20 J/sb10 J/sc2.5 J/sd5 J/s
  13. Overhead telephone wires sag more in summer than in winter because the wirealoses elasticitybis pulled by stronger gravitycexpands in length when heateddmelts at the joints
  14. 100 g of water at 80 °C is mixed with 100 g of water at 20 °C in an insulated vessel. The final temperature of the mixture isa40 °Cb60 °Cc45 °Cd50 °C
  15. According to classical kinetic theory, at absolute zero (0 K) the molecular kinetic energy of an ideal gas isamaximumbinfiniteczerodthe same as at room temperature
  16. An ideal (Carnot) refrigerator works between a freezer at 260 K and a room at 300 K. Its coefficient of performance (heat removed per unit work) isa0.87b1.15c13d6.5
  17. In any irreversible (real) process, the entropy of the universeaincreasesbdecreasescbecomes zerodmust remain constant
  18. Sound waves cannot travel throughasteelbwatercairda vacuum
  19. Taking the speed of sound in air as v ≈ (331 + 0.6 t) m/s, where t is the temperature in °C, its value at 30 °C is abouta331 m/sb349 m/sc360 m/sd320 m/s
  20. An open organ pipe can produce harmonics that areaonly odd multiples of the fundamentalbonly even multiplesconly the fundamentaldall integral multiples (odd and even)
  21. An object is placed 30 cm in front of a concave mirror of focal length 15 cm. The image is formed at a distance ofa10 cm in front of the mirrorb15 cm in front of the mirrorc30 cm in front of the mirrord60 cm in front of the mirror
  22. In an astronomical telescope in normal adjustment, the distance between the objective and the eyepiece isathe difference of their focal lengthsbthe sum of their focal lengthscthe product of their focal lengthsdthe ratio of their focal lengths
  23. The least distance of distinct vision for a normal human eye is abouta10 cmb100 cmc50 cmd25 cm
  24. The beautiful colours seen in a thin soap film or oil film on water are due to the phenomenon ofadispersion alonebdiffractioncinterference of reflected lightdscattering
  25. Polaroid sunglasses cut down the glare from reflecting surfaces by using the phenomenon ofapolarisation of lightbdiffractioncdispersiondtotal internal reflection
  26. A wire of a certain material has a resistance of 4 Ω. A second wire of the same material has twice its length and half its diameter. The resistance of the second wire isa32 Ωb16 Ωc8 Ωd64 Ω
  27. A cell of e.m.f. 2 V and internal resistance 0.5 Ω is connected to an external resistor of 3.5 Ω. The terminal potential difference of the cell isa2.0 Vb1.5 Vc1.25 Vd1.75 V
  28. Electrical appliances in a house are connected in parallel so that every applianceagets the full supply voltage and can be switched independentlybreceives exactly the same current as the otherscuses the minimum possible length of wiredworks safely without any fuse in its plug
  29. In a cyclotron, the frequency with which a (non-relativistic) charged particle revolves in the magnetic fieldaincreases with its speedbis independent of its speedcdepends on the radius of its pathdchanges in every turn
  30. A long solenoid has 1000 turns per metre and carries a current of 2 A. The magnetic field inside it (μ₀ = 4π × 10⁻⁷) is abouta2.5 × 10⁻⁴ Tb1.3 × 10⁻³ Tc2.5 × 10⁻³ Td2.5 × 10⁻² T
  31. Above the Curie temperature, a ferromagnetic substance becomesaparamagneticbdiamagneticca superconductorda permanent magnet of double strength
  32. An electric generator (dynamo) convertsachemical energy into electrical energybmechanical energy into electrical energycheat directly into electricitydlight into electricity
  33. A pure inductor of inductance 0.1 H is connected to a 50 Hz a.c. supply. Its inductive reactance is abouta31 Ωb3.1 Ωc314 Ωd628 Ω
  34. In an a.c. circuit containing only a resistor, the current and the applied voltage area90° out of phase, current leadingb90° out of phase, current laggingcin opposite phasedin phase with each other
  35. Two electric lines of force (field lines) can neverastart from a positive chargebcross (intersect) each othercform open curvesdend on a negative charge
  36. The force between two point charges in air is 0.9 N. When the same charges at the same separation are immersed in a medium of dielectric constant 3, the force becomesa0.3 Nb2.7 Nc0.9 Nd0.03 N
  37. Capacitors of 3 μF and 6 μF are connected in parallel. The combined capacitance isa2 μFb18 μFc4.5 μFd9 μF
  38. In a uniform electric field, the potential falls by 200 V over a distance of 4 cm along the field direction. The field strength isa50 V/mb800 V/mc5000 V/md50,000 V/m
  39. Millikan's oil-drop experiment provided a direct measurement of theaelementary electric charge, ebe/m ratio of the electroncAvogadro numberdwavelength of the electron
  40. The fact that photoelectric emission starts without any time lag, however weak the light, supports theawave theory of lightbphoton (quantum) theory of lightcheating effect of lightdresonance theory
  41. Light from a LASER differs from ordinary light mainly in being highlyaincoherent and whitebcoherent and monochromaticcdivergent in all directionsdpolarised at random
  42. The Lyman series of the hydrogen spectrum is found in theaultraviolet regionbvisible regioncinfrared regiondmicrowave region
  43. A hydrogen electron falls from the n = 2 level to the ground state (ground-state energy −13.6 eV; En = −13.6/n²). The energy of the photon emitted isa10.2 eVb13.6 eVc3.4 eVd12.1 eV
  44. A beta-minus (β⁻) particle emitted by a nucleus is anaa proton knocked out of the nucleusban electron created when a neutron decaysca photon of electromagnetic radiationda helium nucleus of two protons, two neutrons
  45. A radioactive sample has an activity of 8000 decays per second and a half-life of 5 days. Its activity after 15 days will be abouta4000 Bqb1000 Bqc2000 Bqd500 Bq
  46. The control rods of a nuclear reactor, which absorb excess neutrons, are made ofagraphitebheavy waterccadmium (or boron steel)denriched uranium
  47. A light-emitting diode (LED) gives out light when it isareverse biased to breakdownbleft unbiasedcforward biaseddheated strongly
  48. The output of a NOT gate is always theacomplement (inverse) of its inputbsame as its inputclogical 1dsum of its inputs
  49. Neutrinos, produced in nuclear reactions in the Sun, are particles that areaheavy particles carrying a positive chargebphotons of exceptionally high energycparticles each composed of three quarksdneutral, extremely light and very weakly interacting
  50. The best-known evidence for the existence of dark matter in galaxies comes from the study of theathe cycle of sunspots on the Sunbthe ocean tides on the Earthcrotation curves of galaxies (stars orbiting too fast)dthe phases of the Moon through the month

Mental Agility Test (questions 181–200)

  1. Choose the word nearest in meaning to PROMPT (as in "a prompt reply").aLatebImmediatecSlowdCasual
  2. Choose the word most opposite in meaning to TRANSPARENT.aClearbOpaquecGlassydBright
  3. Ship : Captain :: Aeroplane : ?aPassengerbAirportcPilotdSky
  4. Find the odd one out.aKathmandubPokharacNepaldBiratnagar
  5. The scientific study of birds is calledaentomologybornithologycichthyologydherpetology
  6. Find the next number in the series: 3, 7, 13, 21, 31, ?a43b41c39d45
  7. The highest common factor (HCF) of 18 and 48 isa3b12c6d9
  8. The lowest common multiple (LCM) of 4 and 6 isa24b12c10d8
  9. After a 10% price rise, a book costs Rs 550. Its original price wasaRs 495bRs 540cRs 505dRs 500
  10. A speed of 15 m/s is equal toa36 km/hb45 km/hc54 km/hd60 km/h
  11. Statements: All A are B. C is not a B. Which conclusion must be true?aC is an AbAll B are AcSome B are not AdC is not an A
  12. In a code using letter positions joined together (R = 18, A = 1, M = 13, RAM → 18113), the word SITA is coded asa199201b199211c189201d199021
  13. Sunita is older than Gita, Gita is older than Rita, and Rita is older than Mina. Who is the youngest?aSunitabGitacRitadMina
  14. The day before yesterday was Friday. What day is it today?aMondaybSaturdaycThursdaydSunday
  15. Statements: Some doctors are teachers. All teachers are graduates. Which conclusion follows?aAll doctors are graduatesbNo doctor is a graduatecSome doctors are graduatesdAll graduates are doctors
  16. The number of smallest cubes needed to build a solid 3 × 3 × 3 cube isa27b9c18d36
  17. In a plane mirror, the lowercase letter "b" appears as the letteradbbcpdq
  18. A boy walks 4 km north, then turns right and walks 3 km. His shortest (straight-line) distance from the start isa7 kmb1 kmc12 kmd5 km
  19. A circular sheet is folded into quarters, and a small cut is made exactly at the folded corner (which is the centre of the circle). On unfolding, the sheet will haveaone hole at its centrebfour holesctwo holesdeight holes
  20. Which capital letter looks exactly the same after being rotated through half a turn (180°)?aLbNcFdP

Answer key and explanations

Answers — Zoology (1–40)

1. (d) — Neo-Darwinism weds selection to genetics, mutation and population thinking.

2. (d) — Charles Darwin published the Origin in 1859.

3. (b) — Geographic isolation → allopatric speciation.

4. (b) — Arthropod cuticle is chitinous.

5. (a) — Octopus is a cephalopod mollusc.

6. (d) — Tube feet of echinoderms run on the water vascular system.

7. (a) — Pressure is spent pushing blood through the gill capillaries, so systemic flow is comparatively slow and low-pressure — one limitation of the single circuit.

8. (c) — Mast cells release histamine and heparin.

9. (a) — Collagen (ossein) fibres are embedded in the mineralised matrix.

10. (c) — The mucociliary escalator clears the airway.

11. (a) — Adipose tissue is the body's fat store.

12. (c) — Gametocytes mature and fertilise in the mosquito's stomach.

13. (d) — Sleeping hypnozoites in the liver reactivate to cause relapses.

14. (b) — Setae anchor segments while muscles push the worm forward.

15. (d) — The muscular gizzard grinds the swallowed soil.

16. (c) — Bladder, gut and gonoducts all open into the cloaca.

17. (b) — Frog erythrocytes keep their oval nuclei.

18. (d) — The liver makes bile; the gall bladder only stores it.

19. (d) — Ptyalin converts starch to maltose in the mouth.

20. (b) — Rising CO₂/H⁺ is the strongest drive to breathe.

21. (a) — The contracting diaphragm flattens, enlarging the thorax.

22. (c) — The impulse starts in the heart's own SA node: myogenic.

23. (a) — The mitral (bicuspid) valve guards the left AV opening.

24. (c) — Splenic macrophages remove aged red cells.

25. (c) — The glomerular tuft filters into Bowman's capsule.

26. (b) — Without ADH the collecting duct cannot conserve water.

27. (a) — Receptor → afferent → centre → efferent → effector.

28. (a) — Ciliary muscles reshape the lens for accommodation.

29. (c) — Iodine atoms are built into T₃ and T₄ (thyroxine).

30. (b) — Beta cells secrete insulin; alpha cells make glucagon.

31. (d) — The hollow blastocyst implants about a week after fertilisation.

32. (a) — One zygote splits into two genetically identical embryos.

33. (a) — Wuchereria blocks lymphatics, causing elephantiasis.

34. (b) — Activated B cells become antibody-secreting plasma cells.

35. (d) — Edward Jenner vaccinated with cowpox in 1796.

36. (b) — Typhoid is bacterial (Salmonella typhi).

37. (c) — Ultrasound echoes are mapped into an image.

38. (d) — ELISA screens blood for anti-HIV antibodies.

39. (c) — Roots bind the slope and the canopy softens rain impact; clearing exposes soil to erosion and monsoon landslides (the concern behind movements like Chipko).

40. (b) — Ramsar sites are wetlands of international importance.

Answers — Botany (41–80)

41. (b) — Nucleotides are the monomers of DNA and RNA.

42. (a) — Enzymes are (with rare RNA exceptions) proteins.

43. (c) — The capsid is the viral protein shell.

44. (d) — Rod-shaped bacteria are bacilli.

45. (a) — Rhizopus stolonifer is the black bread mould.

46. (c) — Mycorrhizal fungi trade soil minerals with plant roots.

47. (d) — Brown algae store laminarin and mannitol.

48. (a) — A moss spore germinates into an algal-like protonema.

49. (a) — The fern plant is the dominant sporophyte.

50. (c) — Gymnosperm wood conducts through tracheids, typically without vessels.

51. (b) — Brassicaceae flowers have a 4-long + 2-short androecium.

52. (d) — Ecosystem = community + physical environment, interacting.

53. (b) — Succession ends in a self-perpetuating climax community.

54. (b) — Standing crop is the biomass present at one moment.

55. (c) — Pits trap moist air over the pore, cutting water loss.

56. (b) — Plastids pass almost entirely through the egg cytoplasm, giving maternal (cytoplasmic) inheritance — evidence that plastids carry their own DNA.

57. (d) — A cell plate (phragmoplast) partitions the plant cell.

58. (c) — The megaspore mother cell in the nucellus undergoes meiosis.

59. (a) — The glycolate pathway of photorespiration runs through peroxisomes.

60. (c) — Plasmodesmata are cytoplasmic bridges through the walls.

61. (d) — Alleles sit at the same locus on the two homologues.

62. (a) — Both Iᴬ and Iᴮ are expressed: codominance.

63. (b) — One strand runs 5′→3′, its partner 3′→5′ alongside it.

64. (d) — Helicase unzips the helix ahead of the fork.

65. (d) — 61 codons serve 20 amino acids, so most have several codons.

66. (b) — Allolactose (from lactose) binds and disables the repressor.

67. (b) — Bulliform cells lose turgor and roll the blade, saving water.

68. (a) — Heartwood is dead, dark, supportive central xylem.

69. (c) — Palisade cells pack chloroplasts beneath the lit upper surface.

70. (b) — Water moves toward the lower (more negative) water potential.

71. (c) — A potometer tracks water uptake by a transpiring shoot.

72. (d) — Chlorophyll absorbs red (and blue) most; action peaks in red.

73. (b) — Fermentation nets only the 2 ATP of glycolysis.

74. (a) — Peter Mitchell proposed proton-gradient ATP synthesis.

75. (c) — Ethylene is the fruit-ripening hormone.

76. (d) — The tuber is a swollen underground stem; eyes are axillary buds.

77. (a) — Red light (via phytochrome) promotes germination of lettuce seed.

78. (d) — Recombinant human insulin (Humulin) reached patients in 1982.

79. (c) — Leguminous green-manure crops such as dhaincha enrich soil nitrogen.

80. (a) — Liquid nitrogen holds −196 °C, halting metabolism for storage.

Answers — Chemistry (81–130)

81. (a) — 2 mol CH₄ × 2 O₂ each = 4 mol O₂.

82. (d) — 2/18 × 100 ≈ 11.1% hydrogen.

83. (b) — λ = hc/E = 1240/2.55 ≈ 486 nm (in the visible, blue-green region).

84. (c) — The azimuthal number l sets the orbital shape (s, p, d, f).

85. (b) — Fluorine, top-right of period 2, is smallest here.

86. (c) — Every carbon is sp³-bound into a rigid 3D lattice.

87. (d) — Fluorine's electronegativity makes H–F the most polar.

88. (c) — Zn → Zn²⁺ + 2e⁻: it loses electrons (oxidation).

89. (a) — Molar mass = 2 × vapour density = 44.

90. (c) — V = nRT/P = 3 × 0.0821 × 300/2 ≈ 36.9 L.

91. (a) — Kc = (1.0)²/0.5 = 2 (units of mol/L here): products and reactant are comparable.

92. (b) — pH above 7 is alkaline; 9 is weakly so.

93. (d) — Methyl orange is red in acid, yellow in alkali.

94. (c) — Rate ∝ [A]²[B]¹, so the overall order is 2 + 1 = 3.

95. (c) — E°cell = E°cathode − E°anode = 0.34 − (−0.76) = 1.10 V.

96. (a) — By definition ΔH°f of a standard-state element is zero.

97. (d) — Each α removes 4 mass units: (238 − 206)/4 = 8 alpha decays.

98. (b) — Finely divided iron catalyses N₂ + 3H₂ ⇌ 2NH₃.

99. (d) — The Contact process makes H₂SO₄.

100. (a) — Sand and glass are mostly silicon dioxide.

101. (d) — Bleaching powder is CaOCl₂ (calcium oxychloride).

102. (b) — The Hall–Héroult electrolysis uses cryolite to lower the melting point.

103. (a) — Al reduces Fe₂O₃ with enormous heat release.

104. (d) — Soft solder is lead–tin.

105. (d) — Roasting converts sulphides to oxides in excess air.

106. (c) — Na⁺/K⁺ fluxes carry the action potential.

107. (a) — Too little iron → too little haemoglobin → anaemia.

108. (c) — Only electron positions change between canonical forms.

109. (b) — Restricted C=C rotation plus two different groups per carbon.

110. (b) — OH⁻ donates an electron pair: a nucleophile.

111. (d) — LPG is chiefly propane and butane.

112. (b) — Br₂ adds across the double bond.

113. (c) — H₂SO₄ generates NO₂⁺, the nitrating electrophile.

114. (a) — Lone-pair conjugation strengthens (and shortens) the C–Cl bond.

115. (a) — Vigorous oxidation takes ethanol through ethanal to ethanoic acid.

116. (c) — Ether peroxides are dangerously explosive.

117. (b) — Phenol's old name is carbolic acid.

118. (c) — With an α-hydrogen present, ethanal gives the aldol.

119. (d) — Ketones such as acetone do not reduce Fehling's solution.

120. (b) — Soap-making alkaline hydrolysis is saponification.

121. (a) — The largest Ka means the greatest dissociation: HF, with Ka about 40 times that of acetic acid.

122. (a) — Cold HNO₂ diazotises aniline to the diazonium salt.

123. (b) — RCONH₂ + Br₂/NaOH → RNH₂ with loss of the carbonyl carbon.

124. (d) — TNT = 2,4,6-trinitrotoluene.

125. (b) — PVC is polymerised chloroethene.

126. (d) — Alexander Fleming noticed penicillin's action in 1928.

127. (c) — Muriate of potash is potassium chloride.

128. (a) — BaSO₄ is the acid-insoluble white precipitate of the sulphate test.

129. (a) — H₂S blackens lead acetate paper (PbS).

130. (b) — Combustion in the Dumas method releases the nitrogen as N₂ gas.

Answers — Physics (131–180)

131. (b) — Displacement = √(30² + 40²) = 50 m (the path length, 70 m, is the trap).

132. (a) — Velocity has magnitude and direction.

133. (b) — Momentum conservation: v = (0.02 × 400)/4 = 2 m/s.

134. (a) — Force ⊥ displacement at every instant, so no work is done.

135. (c) — KE = ½Iω² = ½ × 2 × 100 = 100 J.

136. (b) — Pressure is transmitted equally (Pascal), so force scales with area: 100 × 50 = 5000 N.

137. (c) — Total energy = ½kA² = 1.0 J; PE at x = 0.05 m is ½ × 200 × 0.0025 = 0.25 J, leaving KE = 0.75 J.

138. (d) — T ∝ 1/√g: smaller g, longer period.

139. (c) — Pulls from all sides cancel; g = 0 at the centre.

140. (b) — K = ΔP/(ΔV/V) = 10⁷/0.005 = 2 × 10⁹ Pa.

141. (d) — Convection needs a flowing medium: fluids.

142. (d) — Conduction rate is proportional to the temperature gradient, so halving ΔT halves the rate to 5 J/s.

143. (c) — Thermal expansion lengthens the wire, increasing sag.

144. (d) — Equal masses of the same liquid: the equilibrium temperature is the mean, (80 + 20)/2 = 50 °C.

145. (c) — Classical kinetic energy vanishes at 0 K.

146. (d) — COP = Tc/(Th − Tc) = 260/(300 − 260) = 6.5.

147. (a) — Total entropy never decreases; it grows in real processes.

148. (d) — Sound needs a material medium.

149. (b) — v = 331 + 0.6 × 30 = 349 m/s.

150. (d) — An open pipe supports all harmonics.

151. (c) — 1/v = 1/f − 1/u = 1/15 − 1/30 = 1/30: the object sits at the centre of curvature, so the image forms there too (same size, inverted).

152. (b) — Foci coincide in normal adjustment: separation = fₒ + fₑ.

153. (d) — The near point of a normal eye is about 25 cm.

154. (c) — Reflections from the two film surfaces interfere.

155. (a) — Reflected glare is partly polarised and can be blocked.

156. (a) — Length ×2 and area ÷4 (diameter halved) multiply R by 8: 4 × 8 = 32 Ω.

157. (d) — I = 2/(3.5 + 0.5) = 0.5 A; terminal p.d. = IR = 0.5 × 3.5 = 1.75 V (0.25 V is lost inside the cell).

158. (a) — Parallel wiring gives each appliance full voltage and its own switch.

159. (b) — f = qB/2πm, independent of speed and radius (classical).

160. (c) — B = μ₀nI = 4π × 10⁻⁷ × 1000 × 2 ≈ 2.5 × 10⁻³ T.

161. (a) — Thermal motion destroys domain alignment; it turns paramagnetic.

162. (b) — A generator turns work into electrical energy by induction.

163. (a) — X(L) = 2πfL = 2π × 50 × 0.1 ≈ 31 Ω.

164. (d) — With pure resistance, current and voltage are in phase.

165. (b) — Intersection would mean two field directions at one point.

166. (a) — A dielectric divides the vacuum force by K: 0.9/3 = 0.3 N.

167. (d) — Parallel capacitances add: 3 + 6 = 9 μF.

168. (c) — E = ΔV/d = 200/0.04 = 5000 V/m.

169. (a) — Millikan measured e, the elementary charge.

170. (b) — Instant emission fits energy arriving in photon packets.

171. (b) — Laser light is coherent, monochromatic and directional.

172. (a) — Transitions down to n = 1 emit ultraviolet lines.

173. (a) — ΔE = 13.6(1/1² − 1/2²) = 13.6 × ¾ = 10.2 eV (the Lyman-α line).

174. (b) — n → p + e⁻ + antineutrino: the β⁻ is that electron.

175. (b) — 15 days = 3 half-lives: 8000 × (½)³ = 1000 Bq.

176. (c) — Cadmium/boron rods swallow neutrons to control the chain.

177. (c) — Forward bias drives recombination that emits photons.

178. (a) — NOT inverts: 1 → 0 and 0 → 1.

179. (d) — Neutrinos barely interact and stream out of the Sun.

180. (c) — Outer stars orbit as if pulled by unseen (dark) mass.

Answers — Mental Agility Test (181–200)

181. (b) — Prompt means immediate, without delay.

182. (b) — Opaque (not see-through) is the opposite of transparent.

183. (c) — A captain commands a ship; a pilot flies an aeroplane.

184. (c) — Nepal is a country; the rest are cities in it.

185. (b) — Ornithology is the study of birds.

186. (a) — Differences are 4, 6, 8, 10, so add 12: 43.

187. (c) — Common factors of 18 and 48 peak at 6.

188. (b) — LCM(4, 6) = 12.

189. (d) — 550 ÷ 1.10 = Rs 500.

190. (c) — 15 × 18/5 = 54 km/h.

191. (d) — If C were an A it would have to be a B; so C is not an A.

192. (a) — S = 19, I = 9, T = 20, A = 1 → 199201.

193. (d) — Sunita > Gita > Rita > Mina in age.

194. (d) — Day before yesterday Friday → yesterday Saturday → today Sunday.

195. (c) — The doctor-teachers are certainly graduates.

196. (a) — 3³ = 27 unit cubes.

197. (a) — Left–right reversal turns b into d.

198. (d) — √(4² + 3²) = 5 km.

199. (a) — All four layers at that corner are the same central point.

200. (b) — N has half-turn (point) symmetry.