8 CHEMISTRY TODAY | FEBRUARY 15ChemistryMusingwasstartedfromAugust'13issueofChemistryTodaywiththesuggestionof Shri Mahabir Singh. The aim of Chemistry Musing is to augment the chances of bright students preparing forJEE(Mainand Advanced)/ AIPMT/ AIIMS/OtherPMTs&PETswithadditionalstudymaterial.IneveryissueofChemistryToday,10challengingproblemsareproposedinvarioustopicsofJEE(Main andAdvanced)/AIPMT.Thedetailedsolutionsoftheseproblemswillbepublishedinnextissueof ChemistryToday.Thereaderswhohavesolvedfveormoreproblemsmaysendtheirsolutions.Thenamesofthosewho sendatleastfvecorrectsolutionswillbepublishedinthenextissue.We hope that our readers will enrich their problem solving skills through "Chemistry Musing" and stand in bettersteadwhilefacingthecompetitiveexams.JEE MAIN/PMTs1.Whichofthefollowingstatementsis/are correct?(I)Alloxoacidsofchlorineundergo disproportionation on heating.(II)ClO2 does not dimerize but Cl2O4 exists.(III) Six ClO bonds in Cl2O7 are the same.(IV) Rb[ICl2] on heating produces RbI + Cl2.(a)II and III(b)II, III and IV(c)I, II and III(d)III only2.TerearethreesamplesofH2O2labelledas 10 vol.; 15 vol.; 20 vol. Half litre of each sample are mixed and then diluted with equal volume ofwater.Calculatevolumestrengthofthe resultant solution.(a)1.339(b)2.68(c)5.0(d)7.53.At300K,thevapourpressureofanideal solutioncontainingonemoleofAandthree molesofBis550mmofHg.Atthesame temperature,ifonemoleofBisaddedto thissolution,thevapourpressureofsolution increasesby10mmofHg.Tevapour pressuresofAandBintheirpurestateare (in mm of Hg)CHEMISTRYCHEMISTRYMUSINGMUSING19pA pB(a)560600(b)600550(c)400600(d)6004004.Te action of Br2/H2O on salicylic acid results in the formation of(a) Br COOHOH(b) Br COOHOHBr (c) Br BrOHBr(d) Br COOHBrBr5.Somestatementsregardingmaleicacidand fumaric acid are given below :(I)pKa1 of maleic acid is greater than pKa1 of fumaric acid.(II)Both maleic acid and its frst conjugate base have intramolecular hydrogen bonding.(III) Fumaricacidcannotformhydrogen bonds.(IV) Ka2offumaricacidislessthanthatof maleic acid.10 CHEMISTRY TODAY | FEBRUARY 15Te incorrect statement(s) is/are(a)II and IV(b)I, III and IV(c)II only(d)all of these.JEE ADVANCED6.Whichofthefollowingstatementsiscorrect for the two molecules, C6H6 and B3N3H6 ?(a)CH bond length is identical with NH and BH bond lengths. (b)Tenatureofdoublebondisperfectly identical in both.(c)Both the molecules are planar.(d)Benzene is more reactive than borazine.COMPREHENSIONTegaswhichstrictlyfollowsthegeneralgas equation,PV=nRTiscalledidealorperfectgas. Actuallynogasisidealorperfectinnature.Tus, van der Waals applied two corrections :He suggested that the pressure exerted by an ideal gas, Pideal is related to the experimentally measured pressure, Preal by the equation :Pideal =Preal+ aV2(for 1 mole of a gas)ObservedCorrectionpressuretermAnothercorrectionconcernsthevolume occupiedbythegasmolecules.Intheidealgas equation, V represents the volume of the container. However,eachmoleculedoesoccupyafnite, althoughsmall,intrinsicvolume,sotheefective volumeofthegasbecomes(Vb)for1moleof a gas.Havingtakenintoaccountthecorrectionsfor pressureandvolume,thegeneralgasequationfor one mole of the gas may be written as : PaV+2(V b) = RTCorrectedCorrectedpressurevolume7.TevanderWaalsconstantaforCO2gas is greater than that of H2 gas. It means that the(a)strengthofvanderWaalsforcesofCO2 gas is less than that of H2 gas (b)strengthofvanderWaalsforcesofCO2 gas is equal to that of H2 gas(c)CO2 gas can be more easily liquifed(d)H2 gas can be more easily liquifed.8.UsingvanderWaalsequation,fndthe constanta(inatmL2 mol2)whenthree molesofagasconfnedina6Lfaskexertsa pressure of 13.0 atm at a temperature of 373 K. Te value of b is 0.05 L mol1.(R = 0.082 L atm K1 mol1)(a)10.47(b)9.39(c)6.46(d)10.74INTEGER VALUE9.Te value of x in the following reaction isClCOC H2 5O(i) moles of Mg x R X(ii) H O/H2+ An alcohol10.Startingwithaninitialpressureof5atmof azoisopropane,40%ofitdecomposesinto nitrogen and hexane vapours in one hour. Te pressure (in atm) exerted by the mixture at this time will bennSolution Senders of Chemistry MusingSET 181.Chirayata Bhattacharyya, Kolkata (West Bengal)2.Agranipanda (West Bengal)SET 171.Sayantan Adhikary (West Bengal)2.Naresh Polam, Narasaraopet (Andhra Pradesh)3.Tejashwini Patil, Bidar (Karnataka)4.Rushikesh Joshi, Nagpur (Maharashtra)CHEMISTRY TODAY | FEBRUARY 15 111.Reactionoft-butylbromidewithsodium methoxide produces(a)isobutane(b)isobutylene(c)sodium t-butoxide(d)t-butyl methyl ether.2.TeionsO2,F,Na+,Mg2+andAl3+are isoelectronic. Teir ionic radii show(a)a signifcant increase from O2 to Al3+(b)a signifcant decrease from O2 to Al3+(c)anincreasefromO2toFandthen decrease from Na+ to Al3+(d)a decrease from O2 to F and then increase from Na+ to Al3+.3.IdentifyAinthefollowingsequenceof reactions :NH31 moleA BCHCl3Alc. KOHCRedn(CH ) CHNHCH3 2 3(a)Ethyl halide(b)iso-Propylamine(c)n-Propyl halide(d)iso-Propyl halide4.Underwhatconditionsoftemperatureand pressure,theformationofatomichydrogen from molecular hydrogen will be favoured the most?(a)High temperature and high pressure(b)Low temperature and low pressure(c)High temperature and low pressure(d)Low temperature and high pressure5.ForanisomerizationreactionAB,the temperature dependence of equilibrium constant is given bylog K = 4 2000TTe value of DS at 300 K is(a)4 R(b)5 R(c)400 R(d)2000 R6.In the given reaction,C7H8 A B Cthe product C is(a)o-bromotoluene(b)m-bromotoluene(c)p-bromotoluene(d)3-bromo-2, 4, 6-trichlorotoluene.7.Te experimental data for the reaction, A + B C is given below :Experiment [A](M)[B](M)Initial rate (mol L1 s1)1 0.50 0.50 1.6 1042 0.50 1.00 3.2 1043 1.00 1.00 3.2 104Te rate equation for the above reaction is(a)rate = k[B](b)rate = k[B]2(c)rate = k[A]2[B]2(d)rate = k[A]2[B]8.Whichofthefollowingsetsofquantum numbers is not possible ?nlmlms(a)3211/2(b)222+1/2(c)1001/2(d)200+1/29.Te ability of anion to bring about coagulation of a given colloid, depends upon(a)magnitude of the charge(b)both magnitude and charge(c)its charge only(d)sign of the charge alone.2015Exam on3 Mayrd12 CHEMISTRY TODAY | FEBRUARY 1510.Te IUPAC name of the compound is(a)4-ethyl-5, 6, 7, 9-tetramethyldeca-2, 9-diene(b)7-ethyl-2, 4, 5, 6-tetramethyldeca-1, 8-diene(c)7-ethyl-2, 4, 5, 6-tetramethyldeca-1, 7-diene(d)7-(1-propenyl)-2, 3, 4, 5-tetramethylnon-1-ene.11.TevalueofthereactionquotientQforthe cell,Zn(s) | Zn2+(aq) (0.01 M) || Ag+(aq) (1.25 M) | Ag(s) is(a)156(b)125(c)1.25 102(d)6.4 10312.WhatisZinthefollowingsequenceof reactions?Phenol Zndust X CH Cl3anhyd. AlCl3 Y KMnO4(alk.) Z(a)Benzene(b)Toluene(c)Benzaldehyde(d)Benzoic acid13.Te position of both, an electron and a helium atomisknownwithin1.0nm.Furtherthe momentumoftheelectronisknownwithin 5.0 1026 kg ms1. Te minimum uncertainty inthemeasurementofthemomentumofthe helium atom is(a)8.0 1026 kg ms1(b)80 kg ms1(c)50 kg ms1(d)5.0 1026 kg ms114.In the reaction,Phenol A CO + HCl2140 C B B is(a)benzaldehyde(b)chlorobenzene(c)benzoic acid(d)salicylic acid.15.Acompoundcontains38.8%C,16.0%Hand 45.2% N. Te formula of the compound would be(a)CH3NH2(b)CH3CN(c)C2H5CN(d)CH2(NH2)216.TeunsaturatedhydrocarbonC6H10which produces OHC(CH2)4CHO on ozonolysis is(a)hex-1-yne(b)hex-2,4-diene(c)cyclohexene(d)1-methylcyclopentene.17.10gofglucose(p1),10gofurea(p2)and 10 g of sucrose (p3) are dissolved in 250 mL of waterat300K.Terelationshipbetweenthe osmotic pressures of the solutions is(a)p1 > p2 > p3(b)p3 > p1 > p2(c)p2 > p1 > p3(d)p2 > p3 > p118.XeOF4 contains(a)sixelectronpairsforminganoctahedron with two positions occupied by lone pairs(b)twop-bondsandtheremainingsix electron pairs forming an octahedron(c)threep-bondsandtheremainingfour electron pairs forming a tetrahedron(d)one p-bond and the remaining six electron pairsforminganoctahedronwithone position occupied by a lone pair.19.Te correct set of oxidation numbers of nitrogen in ammonium nitrate is(a)3, +3(b)1, +1(c)+1, 1(d)3, +520.In a reaction if the initial concentration of the reactantisincreasedfourtimesthentherate becomeseighttimesofitsinitialvalue.Te order of the reaction is(a)2.0(b)3.5(c)2.5(d)1.521.Terootmeansquarespeedofmoleculesof N2gasisu.Ifthetemperatureisdoubledand the nitrogen molecules dissociate into nitrogen atoms, the root mean square speed becomes(a)u/2(b)2 u(c)4 u(d)14 u22.Equal amounts of a solute are dissolved in equal amounts of two solvents A and B. Te lowering ofvapourpressureforthesolutionAistwice the lowering of vapour pressure for the solution B.IfMAandMBarethemolecularweightsof solvents A and B respectively, then(a)MA = MB(b)MA = MB/2(c)MA = 4MB(d)MA = 2MBCHEMISTRY TODAY | FEBRUARY 15 1323.TemaximumpHofasolutionwhichis 0.1MinMg2+fromwhichMg(OH)2isnot precipitated is(Given : Ksp for Mg(OH)2 = 1.2 1011)(a)4.96(b)6.96(c)7.54(d)9.0424.Monomer of n is(a)2-methylpropene(b)styrene(c)propylene(d)ethene.25.A complex of a certain metal ion has a magnetic momentof4.90B.M.Anothercomplexofthe samemetalioninthesameoxidationstate hasazeromagneticmoment.Whichofthe following could be the central metal ion in the two complexes?(a)Mn2+(b)Fe3+(c)Fe2+(d)Cr3+26.Temetalthatdissolvesinliquidammonia, giving a dark blue coloured solution is(a)tin(b)lead(c)sodium(d)silver.27.AnorganiccompoundAhavingmolecular formula C5H10Cl2 is hydrolysed to compound B (C5H10O)whichgivesanoximewith hydroxylamineandyellowprecipitatewitha mixtureofiodineandsodiumhydroxide.Te compound A should be(a)CH3CH2CCl2CH2CH3(b)CH3CH2CH2CCl2CH3(c)CH3CH2CH2CH2CHCl2(d)CH3CH2CH2CHClCH2Cl28.Gas Xcan be easily liquifed in comparison to gas Y. Tis indicates(a)strength of van der Waals forces for X is less than that of Y(b)strength of van der Waals forces for both X and Y is same(c)the value of van der Waals constant a for gas X is greater than that for gas Y(d)the value of van der Waals constant a for gas X is less than that for gas Y.29.Whichofthefollowingwillnotshow geometrical isomerism?(a)[Cr(NH3)4Cl2]Cl(b)[Co(en)2Cl2]Cl(c)[Co(NH3)5NO2]Cl2 (d)[Pt(NH3)2Cl2]30.Consider the following compounds :(i)sulphur dioxide (ii)hydrogen peroxide(iii)ozoneAmongthesecompoundsidentifythosethat can act as bleaching agent(a)i and iii (b)ii and iii(c)i and ii (d)i, ii and iii31.In the following reaction,X Br /HO2 2 Y NaNO/HCl20-5C Z TribromobenzeneX is(a)benzoic acid(b)salicyclic acid(c)phenol(d)aniline.32.Whichofthefollowingreactionswillnot occur?(a)Fe + H2SO4 FeSO4 + H2(b)Cu + 2AgNO3 Cu(NO3)2 + 2Ag(c)2KBr + I2 2KI + Br2(d)CuO + H2 Cu + H2O33.Which one of the following orders is incorrect, with respect to the property indicated?(a)Benzoicacid>phenol>cyclohexanol (acid strength)(b)Aniline>cyclohexylamine>benzamide (basic strength)(c)Formic acid > acetic acid > propanoic acid (acid strength)(d)Fluoroaceticacid>chloroaceticacid> bromoacetic acid (acid strength)34.TreeelementsA,BandCcrystallizeinto acubicsolidlattice.AtomsAoccupythe corners,atomsBthecubecentresandatoms C the edges. Te formula of the compound is(a)ABC(b)ABC2(c)ABC3(d)ABC435.Te following equilibrium constants are given :N2 + 3H2 2NH3 ; K1N2 + O2 2NO ; K2H2 + 1/2 O2 H2O ; K314 CHEMISTRY TODAY | FEBRUARY 15Teequilibriumconstantfortheoxidationof NH3 by oxygen to give NO is(a) KKK2 321(b) KKK2231(c) KKK1 23(d) KKK2 33136.When 3 moles of the reactant A and 1 mole of the reactant B are mixed in a vessel of volume 1 L, the following reaction takes place, A(g) + B(g) 2C(g).If 1.5 moles of C is formed at equilibrium, the equilibrium constant (Kc) for the reaction is(a)0.12(b)0.50(c)0.25(d)4.0037.Tecorrectorderoftheincreasingionic character is(a)BeCl2 < BaCl2 < MgCl2 < CaCl2(b)BeCl2 < MgCl2 < BaCl2 < CaCl2(c)BeCl2 < MgCl2 < CaCl2 < BaCl2(d)BaCl2 < CaCl2 < MgCl2 < BeCl238.Startingwiththreediferentaminoacid moleculeshowmanydiferenttripeptide molecules could be formed?(a)9(b)12(c)6(d)339.Uncertaintyinpositionofanelectron (mass=9.11028g)movingwithavelocity of3104cm/saccurateupto0.001% will be (h = 6.626 1027 erg-second)(a)5.76 cm(b)7.68 cm(c)1.93 cm(d)3.84 cm40.Atroomtemperaturesodiumcrystallisesin abodycentredcubiclatticewithedgelength 4.24 . Te density of sodium will be(a)2.0 g cm3(b)1.0 g cm3(c)23.0 g cm3(d)4.0 g cm341.Whileextractinganelementfromitsore,the ore is ground and leached with dilute solution of sodium cyanide to form the soluble product. Te element is(a)lead(b)chromium(c)manganese(d)silver.42.Numberofmoleculesinonelitreofwateris close to (assuming density of water = 1 g cm3)(a) 1822 4 . 1023(b)55.5 6.023 1023(c) 6 02323 4.. 1023(d)18 6.023 102343.Te following sequence of reactions on A givesCHCONH2 2COOCH3(i) Br/NaOH2(ii) A(a)(b) (c)(d) 44.Whichofthefollowinghydridesofgroup 16elementshaslowestthermalstabilityand maximum acid strength?(a)H2S(b)H2O(c)H2Se(d)H2Te45.In which of the following pairs, there is greatest diferenceintheoxidationnumbersofthe underlined elements?(a)NO2 and N2O4(b)P2O5 and P4O10(c)N2O and NO(d)SO2 and SO3SOLUTIONS1.(b) : CH3CH CBr + NaOCH3 3CH3+ ::tert-Butyl bromideSod. methoxide CH CCH + NaBr + CH OH3 2 3CH32-Methylpropene(Isobutylene)2.(b) :Amongst isoelectronic ions, ionic radii of anionsismorethanthatofcations.Further, sizeoftheanionincreaseswithincreasein vechargeandsizeofcationdecreaseswith increase in +ve charge. Hence, the correct order of ionic radii is O2 > F > Na+ > Mg2+ > Al3+.CHEMISTRY TODAY | FEBRUARY 15 153.(d) :CH3CH3CH XNH31 moleCH3CH3CHNH2CHCl3Alc. KOH( ) A ( ) BCH3CH3CHNHCH3CH3CH3CHNC( ) CReduction4.(c) :H2(g) H(g) + H(g); DH = +veAccordingtoLe-Chateliersprinciple,the forwardreactionisfavouredbylowering pressure(asnumberofgaseousmolesare increasing) and by increasing temperature as it is endothermic.5.(a) :VariationofKwithtemperatureisgiven bylog K = SRHRT2 303 .log K = 4 2000T (given)\ SR = 4 DS = 4 R6.(b) : 3Cl2CH3Br /Fe2CCl3(CH)7 8( ) AZn/HClCCl3BrCH3Brm-Bromotoluene( ) C( ) B7.(a) :Rate = k[A]x[B]yFrom exp. 1 and 2, we get1 6 103 2 100 50 0 500 50 1 001244..( . ) ( . )( . ) ( . )= = kkx yx yyy = 1From exp. 2 and 3, we get3 2 103 2 100 50 1 001 00 1 0044..( . ) ( . )( . ) ( . )=kkx yx y1 = 12x12120= x x = 0Hence, rate equation will berate = k[A]0[B]1rate = k[B]8.(b)9.(b) :Bothmagnitudeandnatureofcharge afectcoagulationofagivencolloid.Greater themagnitudeofthevecharge,quickerwill be the coagulation of +vely charged colloid.10.(b) : 7-Ethyl-2, 4, 5, 6-tetramethyldeca-1, 8-diene11.(d) :Te cell reaction isZn(s) Zn2+(aq) (0.01 M) + 2e[Ag+(aq)(1.25 M) + e Ag(s)] 2Zn(s) + 2Ag+(aq) (1.25 M) Zn2+(aq)(0.01 M) + 2Ag(s)Q = = = ++[ ][ ].( . ).ZnAg22 230 011 256 4 1012.(d) : OH CH3COOHZndustCHCl33anhy. AlClBenzene( ) XToluene( ) YKMnO (alk.)4Benzoic acid( ) ZPhenol13.(d) :According to uncertainty principle, Dx Dp = h4As,Dx=1.0nmforbothelectronand heliumatom,soDpisalsosameforboththe particles.Tus, uncertainty in momentum of the helium atom is also 5.0 1026 kg ms1.14.(d) : OH ONa OHCOOHNaOHCO2HClPhenol( ) A( ) BSalicylic acid16 CHEMISTRY TODAY | FEBRUARY 1515.(a) : Element % At. wt. Molar ratioSimplest ratioC 38.8 12 3.23 1H 16.0 1 16.0 5N 45.2 14 3.23 1Empirical formula = CH5N or CH3NH216.(c) :Sincetheunsaturatedhydrocarbonon ozonolysisgivesasinglecompound,having two aldehydic groups, it must be cyclic.(CH)2 4CHOCHOor (CH)2 4CHCHCyclohexeneO3Zn/HO217.(c) :p = nRTV, p = wRTMV\p 1MMol.wtsofglucose,ureaandsucroseisinthe order : sucrose > glucose > ureaHence,theorderoftheirosmoticpressuresis urea > glucose > sucrose i.e., p2 > p1 > p318.(d) 19.(d) :[NxH4]+ [NyO3]x + 4 = +1 x = 3; y 6 = 1y = +520.(d) :Rate = k[A]norr = k[A]n(i)8r = k(4[A])n(ii)Dividing eqn (ii) by (i), we get23 = 22nor2n = 3n = 1.521.(b) :(urms)1 = 311RTM,for N2 molecule, M1 = 28.(urms)2 = 322RTM,for N atom, M2 = 14.( )( )uuRTMRTMRTMMRTrmsrms12112211223333= = == =TT111428 21412(urms)2 = 2(urms)1 = 2 u22.(d) : p ppxnnAAA = =...(i)p ppxnnBBB = =...(ii)By dividing eqn (i) by (ii), we get p ppp ppnnwMMwMMABBA BA AB = = =2 = MMAB MA = 2MB23.(d) :Mg(OH)2 Mg2+ + 2OH,Ksp = [Mg2+][OH]21.2 1011 = 0.1 [OH]2[OH]2 = 1.2 1010 [OH] = 1.1 105[H+] = 1014/(1.1 105) = 9.09 1010 MpH = log [H+]= log (9.09 1010)= 10 0.9586 = 9.0424.(a)25.(c) :Sincethemagneticmomentoftheone complex is 4.90 B.M. so the metal ion contains 4 unpaired electrons.Since another complex of the same metal ion in thesameoxidationstateshowszeromagnetic moment, so in this complex there is no unpaired electron. Tis is possible in d6 confguration.Mn (25):3d54s2; Mn2+: 3d5Fe (26):3d64s2; Fe3+: 3d5Fe (26) :3d64s2; Fe2+: 3d6Cr (24) :3d54s1; Cr3+: 3d326.(c) :Allthealkalimetalsdissolveinliquid ammonia giving deep blue coloured solutions.27.(b) : CHCHCHCCl CH3 2 2 2 3CHI CHCHCHCOCH3 3 2 2 3Oxime( ) ACHCHCHC(OH)CH3 2 2 2 3HO2I/OH2( ) B IodoformNHOH2HO228.(c)CHEMISTRY TODAY | FEBRUARY 15 1729.(c) :OctahedralcomplexesofthetypeMA5B do not show any geometrical isomerism.30.(d)31.(d) : Br /HO2 2NH2NaNO /HCl20-5C( ) XNH2Br BrBr( ) YCHOH2 5boilNCl2Br BrBrBr BrBr( ) Z+32.(c) :I2isweakeroxidisingagentthanBr2 therefore, it is unable to displace bromine.33.(b) :Basic strength decreases as, cyclohexylamine > aniline > benzamide.Lesserbasicityofanilineandbenzamideis due to participation of lone pair of electrons of NH2 group in resonance.Amides are much less basic than amines.34.(c) :No. of A atoms per unit cell = 8 18 = 1No. of B atoms per unit cell = 1No. of C atoms per unit cell = 12 14 = 3Ratio A : B : C = 1 : 1 : 3.Hence, the formula is ABC3.35.(d) :N2 + 3H2 2NH3 ;K1322 23=[ ][ ][ ]NHN H(i)N2 + O2 2NO ;K222 2=[ ][ ][ ]NON O(ii)H2 + 12O2 H2O;K3 =[ ] H O[H ][O ]22 21/2 (iii)For the reaction, 2NH3 + 52O2 2NO + 3H2O;K =[ ] [ ][ ] [ ]/NO H ONH O22 33225 2= [ ][ ] [ ][ ][ ] [ ][ ][ ][ ]/NON OH OH ON HNH222 223323 22 2332= K KK2 33136.(d) :A(g) + B(g) 2C(g)Initial moles310 Moles at eqm3x1x2xGiven that 2x = 1.5 x = 1.5/2 KCA Bxx xc = = [ ][ ][ ]( )( )( )2 223 1( volume of vessel = 1 L) Kxx xc = 43 12( )( )Kc == =( . ). .1 52 25 0 25100254237.(c) 38.(c)39.(c) :Mass of an electron (m) = 9.1 1028 g; Velocity of electron (v) = 3 104 cm/s; Accuracy = 0.001% = 0.001100 and Plancks constant(h) =6.626 1027 erg-second.We know that actual velocity of the electron (Dv)= 3 104 0.001100 = 0.3 cm/sTerefore,uncertaintyinthepositionofthe electron( ).( . ) .xhmv= = 46 626 104 9 1 10 0 32728( ).( . ) .xhmv= = 46 626 104 9 1 10 0 32728 = 1.93 cm40.(b) 41.(d)42.(b) :1 litre of H2O weighs = 1000 g= 100018 = 55.55 moles\No. of molecules in 1 L of H2O= 55.55 6.023 102343.(c) : CHCONH2 2COOCH3Br/NaOH2(Hofmannbromamide reaction)AONHOCHNH2 2OCH3CHOH344.(d) :H2O, H2S, H2Se, H2Te Thermal stability decreasesAcidic strength increases45.(d)nn18 CHEMISTRY TODAY | FEBRUARY 151.Acylinderofcompressedgasthatbearsno label is supposed to contain either ethylene or propylene.Combustionofthesampleshows that 12 cm3 of the gas requires 54 cm3 of oxygen forcompletecombustion.Tisindicatesthat the gas is(a)only ethylene(b)only propylene(c)1 : 1 mixture of the two gases(d)some unknown mixture of the two gases.2.Ered of diferent half-cells are given :ECu2+/Cu = 0.34 V;EZn2+/Zn = 0.76 V;EAg+/Ag = 0.80 V;EMg2+/Mg = 2.37 VIn which cell is DG most negative?(a)Zn | Zn2+ (1 M) | | Mg2+ (1 M) | Mg(b)Zn | Zn2+ (1 M) | | Ag+ (1 M) | Ag(c)Cu | Cu2+ (1 M) | | Ag+ (1 M) | Ag(d)Ag | Ag+ (1 M) | | Mg2+ (1 M) | Mg3.On the basis of given reduction potential data, EFe2+/Fe = 0.44 V, ECu2+/Cu = 0.34 V,EAg+/Ag = 0.80 Vwhich of the following statements is correct?(a)Cu displaces Fe from FeSO4 solution(b)Ag displaces Cu from CuSO4 solution(c)Fe displaces Cu from CuSO4 solution(d)None of these4.Identify X in the following reaction,XKOHCH3CH3O(a) O O(b) OO(c) O O(d)None of these5.TefactorofDGvaluesisimportantin metallurgy.TeDGvaluesforthefollowing reactions at 800C are given as :S2(g) + 2O2(g) 2SO2(g); DG = 544 kJ2Zn(s) + S2(g) 2ZnS(s); DG = 293 kJ2Zn(s) + O2(g) 2ZnO(s); DG = 480 kJTe DG for the reaction,2ZnS(s) + 3O2(g) 2ZnO(s) + 2SO2(g) will be(a)731 kJ(b)773 kJ(c)229 kJ(d)357 kJ6.Ironexhibits+2and+3oxidationstates. Whichofthefollowingstatementsaboutiron is incorrect?(a)Ferrous oxide is more basic in nature than the ferric oxide.(b)Ferrouscompoundsarerelativelymore ionicthanthecorrespondingferric compounds.(c)Ferrouscompoundsarelessvolatilethan the corresponding ferric compounds.(d)Ferrouscompoundsaremoreeasily hydrolysedthanthecorrespondingferric compounds.7.AmongLiCl,RbCl,BeCl2,MgCl2,the compoundswithmostandleastionic character respectively are(a)LiCl and RbCl(b)RbCl and BeCl2(c)RbCl and MgCl2(d)MgCl2 and BeCl2Practice Paper 2015Examon4 AprilthCHEMISTRY TODAY| FEBRUARY 15 198.Tedensityofanioniccompound(mol.wt. 58.5)is2.165gcm3andtheedgelengthof unitcellis562pm,thentheclosestdistance between A+B and rank of unit cell is(a)281 pm, 4(b)562 pm, 2(c)562 pm, 4(d)281 pm, 29. Conc. HNO3conc. H SO , 333 K2 4ZnDistillationA BZnNaOH( .) aqCPhenolIntheabovereactionsequence,A,BandC respectively are (a)benzene, nitrobenzene, aniline(b)benzene, m-dinitrobenzene, m-nitroaniline(c)toluene, m-nitrotoluene, m-toluidine(d)benzene, nitrobenzene, hydrazobenzene.10.Whichofthefollowingpairsofstructures representsfacialandmeridionalisomers respectively?(a) HN3HN3CoClClClNH3andHN3HN3CoClClClNH3(b) HN3HN3CoClClNH3andHN3HN3CoClClNH3ClCl(c) HN3HN3CoClClNH3andHN3HN3CoClClNH3Cl Cl(d) HN3CoClClNH3andHN3CoClNH3ClClNH3NH3Cl11.AgasXispassedthroughwatertoforma saturatedsolution.Teaqueoussolutionon treatmentwithsilvernitrategivesawhite precipitate. Te saturated aqueous solution also dissolves magnesium ribbon with evolution of a colourless gas Y.X and Y respectively are(a)CO2, Cl2(b)Cl2, CO2(c)Cl2, H2(d)H2, Cl212.Acertainbufersolutioncontainsequal concentrationofXandHX.IfKbforXis 1010, calculate the pH of bufer.(a)1(b)2(c)3(d)413.Which of the following compounds would have the smallest value for pKa?(a)CHF2CH2CH2COOH(b)CH3CH2CF2COOH(c)CH3CF2CH2COOH(d)CH3CH2CH2COOH14.Teelectrongainenthalpies(inkJmol1)of halogens X, Y and Z are respectively 349, 333 and 325. Ten X, Y and Z respectively are(a)F, Cl and Br(b)Cl, F and Br(c)Cl, Br and F(d)Br, Cl and F15.Arrangeindecreasingorder,theenergyof2s orbital in the atoms H, Li, Na, K.(a)E2s (H) > E2s (Li) > E2s (Na) > E2s (K)(b)E2s (H) > E2s (Na) > E2s (Li) > E2s (K)(c)E2s (H) > E2s (Na) = E2s (K) > E2s (Li)(d)E2s (K) > E2s (Na) > E2s (Li) > E2s (H)16.In Cannizzaro reaction given below :2PhCHO :OH PhCH2OH + PhCOOthe slowest step is (a)the attack of :OH at the carbonyl group(b)the transfer of hydride to the carbonyl group(c)theabstractionofprotonfromthe carboxylic group(d)the deprotonation of PhCH2OH.17.Peroxide ion(i)hasfvecompletelyflledantibonding molecular orbitals.(ii)is diamagnetic.(iii) has bond order one.(iv) is isoelectronic with neon.Which of these are correct?(a)(ii) and (iii)(b)(i), (ii) and (iv)(c)(i), (ii) and (iii)(d)(i) and (iv)20 CHEMISTRY TODAY | FEBRUARY 1518.Teproductformedduringb-eliminationin the reaction isI.(CH) CHCHCH3 2 3BrCHOH2 5CHONa2 5II.(CH) CHCHCHBr3 2 2 2CHOH2 5CHONa2 5(a)only 2-methylbut-2-ene in I and II(b)3-methylbut-1-eneinIIand2-methylbut-2-ene and 3-methylbut-1-ene in I(c)2-methylbut-2-ene and 3-methylbut-1-ene in II and 2-methylbut-2-ene in I.(d)none of the above.19.Te reaction, 2AB(g) + 2C(g) A2(g) + 2BC(g)proceeds according to the mechanism :(I)2AB A2B2(fast)(II)A2B2 + C A2B + BC(slow)(III) A2B + C A2 + BC(fast)Whatwillbetheinitialratetaking[AB]= 0.2Mand[C]=0.5M?TeKcforthestepI is102M1andrateconstantforthestepIIis 3.0 103 mol1 L min1.(a)0.0716 M min1(b)0.0891 M min1(c)0.006 M min1(d)0.0257 M min120.Cyclopropanoic acidNH, heat3XKOH/Br2YCHCl /KOH3 ( .) alcZHO3+Carboxylic acid( ) ATefnalproduct(s)intheabovesequenceof reactions is/are(a)HCOOH only(b)HCOOH and Y(c)CH3NH2 and A(d)A and X21.At 20C, the osmotic pressure of urea solution is400mm.Ifthesolutionisdilutedandthe temperature is raised to 35C, then the osmotic pressure is found to be 105.3 mm. Te solution is diluted to(a)6 times(b)4 times(c)2 times(d)8 times.22.Teammoniaevolvedfromthetreatment of0.30gofanorganiccompoundforthe estimationofnitrogenwaspassedin100mL of0.1Msulphuricacid.Teexcessofacid required20mLof0.5Msodiumhydroxide solutionforcompleteneutralization.Te organic compound is(a)acetamide(b)benzamide(c)urea(d)thiourea.23.Consider the following reactions :I.AlH3 + H AlH4II.H2O + H H2 + OHSelectcorrectstatementbasedonthese reactions.(a)HactsasLewisacidinIandLewisbase in II.(b)H acts as Lewis base in I and Bronsted base in II.(c)H acts as Lewis acid in I and Bronsted acid in II.(d)H acts as Lewis base in I and II.24.Which of the following oxoacids of phosphorus isareducingagentandamonobasicacidas well?(a)H3PO2(b)HPO3(c)H3PO3(d)H4P2O525.Anoxideofnitrogenhasvapourdensity46. Find the total number of electrons in its 92 g.(a)46 NA(b) NA46(c)92 NA(d) NA9226.AhexapeptidehasthecompositionAla,Gly, Phe, Val. Both the N-terminal and C-terminal unitsareVal.Cleavageofthehexapeptideby chemotrypsingivestwodiferenttripeptides, bothhavingValastheN-terminalgroup. Amongtheproductsofrandomhydrolysis, one is Ala-Val dipeptide fragment. What is the primary structure of the hexapeptide?(a)Val-Gly-Phe-Val-Ala-Val(b)Val-Ala-Phe-Val-Gly-Val(c)Val-Gly-Ala-Val-Phe-Val(d)Val-Phe-Val-Ala-Gly-ValCHEMISTRY TODAY| FEBRUARY 15 2127.Tefreezingpointdepressionof0.1molal solutionofaceticacidinbenzeneis0.256K, Kfforbenzeneis5.12Kkgmol1.What conclusioncanyoudrawaboutthemolecular state of acetic acid in benzene?(a)Acetic acid is doubly associated.(b)Benzene is doubly associated.(c)Both are equally associated.(d)None of the above.28.N2 is passed through overheated CaC2. Which ofthefollowingstatementsarecorrectforthe product formed?I.State of hybridisation of C is sp.II.Ureaisanintermediateformedduring hydrolysis of the above product.III.Anionpresentintheproductisnota pseudohalide ion.IV.Hydrolysis of the product gives rise to NH3 gas slowly.(a)I, II and III(b)III and IV(c)I, II and IV(d)None of these.29.AvesselhastwoequalcompartmentsAand BcontainingH2andO2respectively,each at1atmpressure.Ifthewallseparatingthe compartment is removed, the pressure(a)will remain unchanged in A and B(b)will increase in A and decrease in B(c)will decrease in A and increase in B(d)will increase in both A and B.30.Identify the fnal product in the reaction, CHCHO +3MgBr( ) A ( ) BHBr H/+HO2(a) Br(b) BrCH3(c) BrCH3(d) BrCH3SOLUTIONS1.(b) : (i) CH2 CH2 + 3O2 2CO2 + 2H2OEthylene12 cm336 cm3(ii) CH3CH CH2 + 92O2 3CO2 + 3H2OPropylene12 cm312 92= 54 cm3Tus,12cm3ofpropylenerequires54cm3of O2 and hence, cylinder contains only propylene.2.(b) : (a) Zn | Zn2+ (1 M) | | Mg2+ (1 M) | MgEcell= Ecathode Eanode = EMg2+/Mg EZn2+/Zn= 2.37 (0.76) = 1.61 VDG= nFEcell = 2 96500 (1.61)= +310,730(b)Zn | Zn2+ (1 M) | | Ag+ (1 M) | AgEcell= EAg+/Ag EZn2+/Zn= 0.80 (0.76) = +1.56 VDG= nFEcell = 2 96500 1.56 = 301,080(c)Cu | Cu2+ (1 M) | | Ag+ (1 M) | AgEcell= EAg+/Ag ECu2+/Cu = 0.80 0.34 = +0.46 VDG= nFEcell = 2 96500 0.46 = 88,780(d)Ag | Ag+ (1 M) | | Mg2+ (1 M) | MgEcell= EMg2+/Mg EAg+/Ag = 2.37 0.80 = 3.17 VDG= nFEcell = 2 96500 (3.17)= +611,8103.(c): Fe + Cu2+ Fe2+ + Cu(i)E = EFe/Fe2+ + ECu2+/Cu = 0.44 + 0.34 = 0.78 VTus,reaction(i)isspontaneousmeansFe displaces Cu from CuSO4 solution.2Ag + Cu2+ 2Ag+ + Cu(ii)E = EAg/Ag+ + ECu2+/Cu = 0.80 + 0.34 = 0.46 VTus,reaction(ii)isnotspontaneousmeans Ag cannot displace Cu from CuSO4 solution.4.(b) : OO ( ) XKOHOOOHOHO2O22 CHEMISTRY TODAY | FEBRUARY 155.(a) : S2(g) + 2O2(g) 2SO2(g); DG = 544 kJ(i)2Zn(s) + S2(g) 2ZnS(s); DG = 293 kJ (ii)2Zn(s) + O2(g) 2ZnO(s); DG = 480 kJ (iii)Te required equation is2ZnS(s) + 3O2(g) 2ZnO(s) + 2SO2(g)which is obtained by (i) + (iii) (ii)\DG= 544 + (480) (293)= 544 480 + 293 = 731 kJ6.(d) : (a) FeO > Fe2O3 (basic).(b)FeCl2>FeCl3(ionic),higherthecharge, greaterthepolarizingpowerandthus,greater the covalent nature.(c)Fe2+saltsaremoreionichence,less volatile than Fe3+ salts.(d)Greaterthecovalentnature,moreeasily they are hydrolysed. Tus, FeCl3 is more easily hydrolysed than FeCl2.7.(b) : AccordingtoFajansrule,thesmaller thesizeandhigherthechargeonthecation, greateristhecovalentcharacteroftheionic bond.Hence,BeCl2ismostcovalenti.e.,least ionic character while RbCl is least covalent i.e., most ionic character.8.(a) : =Za NAmol. wt.32.165 = =ZZ58 5562 10 6 10410 3 23.( )\AB has fcc structure,\daA B+ = = =25622281pm9.(d) : CHOH6 5ZndistillationCH6 6HNO+ HSO3 2 4333 KCHNO6 5 2Zn/NaOH( .) aqHydrazobenzeneCHNHNHCH6 5 6 5Phenol Benzene( ) ANitrobenzene( ) B ( ) C10.(a) : Inoctahedralcomplex [Ma3b3] Facial (fac) : 3 donor atoms ofsameligandsoccupyadjacent positions at the corners.abaa bbMMeridional(mer):Whenthepositionsare around the meridian.abbbaa11.(c): Cl2 + H2O HClO + HCl(X)AgNO3 + HCl AgCl + HNO3White ppt.Mg + 2HCl MgCl2 + H2(Y)12.(d) : According to Handersons equation,pH= log Ka + log[Salt][Acid](i)Given that, Kb = 1010andKa Kb = 1014\ Ka=10101410 = 104and[Salt] = [Acid]Putting these values in eq. (i),pH = log 104 = 413.(b) : SmallestvalueofpKameansstrongest acid,I-efectofFismaximumin CH3CH2CF2COOHandhence,itisthe strongest acid.14.(b) : Amongsthalogens,chlorinehasmost negative electron gain enthalpy. So, the correct order is Cl(349) > F(333) > Br(325) > I(296)15.(a) : Asatomicnumber(nuclearcharge) increases, all the orbitals are pulled closer to the nucleus. Closer is an orbital to the nucleus, less is its energy.16.(b) : Rate determining step is always the slowest step. In case of Cannizzaro reaction, H transfer tothecarbonylgroupistheratedetermining step and hence the slowest.CHEMISTRY TODAY| FEBRUARY 15 23Mechanism :CH C O + OH6 5Fast+ OCH6 5CHOHO C CH6 5HSlow,Hydride transferCH C O + O C CH6 56 5OHHHCHCOO+ CHCHOH6 56 5 2HRearrangement17.(a) : Peroxide ion is O22O22 (18) : s1s2, s*1s2, s2s2, s*2s2, s2pz2,(p2px2 = p2py2), (p*2px2 = p*2py2)Bond order===N Nb a210 821Itcontainsfourcompletelyflledantibonding molecularorbitals.Since,alltheelectronsare paired,O22isdiamagnetic.Peroxideionis isoelectronic with argon, not with neon.18.(b) : I. Br12 34+43213-Methyl-but-1-ene2-Methyl-but-2-eneII. Br43123-Methylbut-1-ene19.(c): Rate of reaction = Rate of step II(the slowest step) Rate of reaction [A2B2][C] = k[A2B2][C](i)where k is the rate constant, of step II.Te equilibrium constant, Kc for the step I isKA BABA B K ABc c= [ =[ ][ ]] [ ]2 222 22Putting this in equation (i), we getRate of reaction = kKc[AB]2[C]= k[AB]2[C] [AB]2[C](ii)where k = kKc = rate constant of reaction.Equation (ii) is the rate law of reaction,initial rate = 3.0 103 102 (0.2)2(0.5)= 0.3 0.04 0.5 = 0.006 M min120.(b) : ( ) YCOOHNH,3CONH2KOH/Br2H N2CHCl ,3KOH( .) alcNCHO3+HydrolysisHCOOH + NH2Cyclopropanoic acid( ) X( ) Y ( ) Z( ) A21.(b) : p = 400760 atm, T = 293 KNow using, pV = nRT 400760 V1 = n R 293(i)Aferdilution,letvolumebecomesV2and temperature is raised to 35C, i.e., 308 K, andosmoticpressurechangesto,p= 105 3760.atm, then 105 3760. V2 = n R 308(ii)Dividing eqn. (i) by (ii), we get VV12293308105 3400= . V2 = 4V1Hence, the solution is diluted to 4 times.22.(c): Let unreacted 0.1 M(= 0.2 N) H2SO4 = V mL20mLof0.5N(=0.5M)NaOH=VmLof 0.2 N H2SO420 0.5 = V 0.2V = 20 0 50 2 .. = 50 mLUsed H2SO4 = 100 50 = 50 mL% of N = 1 4 . Normality of acid Vol. of acid usedMass of substance taaken= =1 4 0 2 500 3046 67. ... % % of N in(a)CH3CONH2 = 14 10059 = 23.73%(b)C6H5CONH2 = 14 100121 = 11.57%24 CHEMISTRY TODAY | FEBRUARY 15(c)NH2CONH2 = 28 10060 = 46.67%(d)NH2CSNH2 = 28 10076 = 36.84%23.(b)24.(a) : AcidswhichcontainPHbondshave strongreducingproperties.Hypophosphorous acid(H3PO2)isagoodreducingagentasit contains two PH bonds.POHHOH(Monobasic)25.(a) : Let the oxide of nitrogen be N2OxMol. wt. of N2Ox = 46 2 = 92\2 14 + 16(x) = 92 x = 4\Oxide is N2O492 g of N2O4 = 1 mole of N2O4= NA molecules of N2O41 molecule of N2O4 has 46 electrons.\NA molecules of N2O4 has 46 NA electrons.26.(a) : Val-Gly-Phe-Val-Ala-Val,itsrandom hydrolysisgivesAla-Valdipeptidefragment whichindicatestheconnectedpresenceof Ala and Val.27.(a) :i =observed colligative propertycalculated colligative propeerty= =0 2560 51212..Also,i =calculated molecular massobserved molecular massCalculated molecular mass of CH3COOH = 60\Observed molecular mass = 601 2 / = 120Hence, acetic acid exists as doubly associated.28.(c): CaC2 + N2 1100C CaNCN + CCalciumcyanamideCa2+[N C N]2linear shape (sp-hybridised C- atom)Onhydrolysis,calciumcyanamidegets convertedintoureawhichthendecomposes into ammonia.CN22 is pseudohalide ion.29.(a) : Initially the product PV in compartments A and B = 1 V + 1 V = 2V if volume of each compartment is V.NowPV=constantatconstanttemperature andifwallisremoved,thenVbecomes2V, thuspressureshouldbe1atmtohave PV constant.30.(b) : CHCHO +3MgBr COHHCH3COH2HCH3+( ) AHO2+HCH3+CH3BrCH3BrHBr+ H/+HO2nnWinners of January 2015 CrosswordArindam Sen, Purulia (West Bengal)A.K Prasad, Guwahati (Assam)VenkateshPurushotham:Crosswordhelpsustoexplore and enhances our thinking capacity.Senders of December 2014 CrosswordRushikesh Joshi, Nagpur (Maharashtra)Z Q U A R TTURGOWELVEA K A L O I DANHYSRONE P U RMP LU L S I NTHYMOALNICOA R B O G E NKIETICSM U R I A T C A C DLEVIGATIONKWSHIORKORMLACHITEGREENO F C A S S SWARTSUO Z O K E R I T EH Y D R O M ECT R A H E D R NROFUGET E RVOLUM A G N E S I MELO V R V O L T A G EC H R M I U MFLYASHT ESOLUTIONS TO JANUARY 2015 CROSSWORDCHEMISTRY TODAY| FEBRUARY 15 25ONLY ONE OPTION CORRECT TYPE1. (CH)4 2COOHCOOHEtONa+?(a) OO(b) OHC3(c) OHC3(d)None of these.2. 2CH2COOEtCOOEtEtONa (excess) +EtOHACHI22S 2NBstrong base/alcoholCxS 2NCH2CH2CCOOEtEtOOCCH2C EtOOCCOOEtdil. KOHDHO,3+EIdentifyxandE(whichshouldbemost suitable).(a)x = CH2I2/Zn; E = (b)x = CH Br2CH Br2, E = (Aromatic):(c)x = CH Br2CH Br2, E =COOH(d)None of these.3.Identify the product. ONH2Ph ?(a) NHPh(b) PhONH2(c) NH2O+ PhH(d)None of these.4. OCH3Me SiCl3LDAOSiMe3CH3+OSiMe3CH3( ) x( ) y* Institute of Chemistry (IOC)- Asansol, Durgapur, Dhanbad, Burdwan, Kolkata, Jamshedpur, Bokaro, Patna 09732313208Dear students !! Already the bell has rung and you all are ready to welcome the season of exams. Now, the only mantra is practice, practice and practice. Every week take atleast two full length tests. Presenting JEE Advanced practice paper inorganicchemistry. Themajorthingis,youhavetonishitwithin45minutes.Itssolutionswillbepublishedinthe next issue. Till then good bye !!*Arunava Sarkar26 CHEMISTRY TODAY | FEBRUARY 15(a)x is slightly greater than y.(b)x is slightly lesser than y.(c)y is largely greater than x.(d)Reaction does not proceed without heat.5.CH C CH3 3OSeO2MethylglyoxalWhi chof t hefol l owi ngst atement si s correct?(a)React i oni si nbet weenSeO2and CH C CH3 3O directly.(b)React i oni si nbet weenSeO2and CH C CH2 3O H actually.(c)ReactionisinbetweenH2SeO3and CH3COCH3.(d)None of these.6.Identify the product. CD CHO + 4HCHO3OH?(a)HOH C C CH OH2 2CH OH2CH OH2(b)CCH CH OH2OHDDD (only one HCHO will participate)(c)Conditionsarenotsufficientforthe reaction to occur.(d)CD3CHO will not take part. HCHO will undergo Cannizzaro reaction.7. NO2CH CH2OSeO2ANaOHBIdentify B in the reaction sequence.(a)NO2groupatthemetapositionwill deactivatetheringanditwillnotallow any reaction.(b)As NO2isabiggroup,SeO2will causeoxidationatCHOposition andwillconvertittoCOOH.So,Bis NO2CH C ONa2O+(c)PhCCHO O+ NO2(d) NO2CHC ONaO+OH8. PhCHO + HCHOCa(OH)2No. of products = ?(a)2(b)4(c)1 (d)6 (including crossover products)9. CH CH CCH CH CH CH SMe3 2 2 2 2 2 2+OBuLiX.+.here, X is the major product. Identify X.(a) Et(b) Et(c)(d)None of these.10. NMeMeOCH3+Major product = ?(a)(b) (c)(d)None of these.11. CH3HNMe3H+H C5 2Major product = ?CHEMISTRY TODAY| FEBRUARY 15 27(a) CH3(b) C H2 5(c) CH3C H2 5(d)None of these.12. OHOHMnO2?(a) OO(b) OHO(c) OOH(d)None of these.13. OHMnO2ACHCHONa3 2B +CHCHOH3 2B = ?(a) COOH(b) COOH(c) COOHO(d) HOOCH CH3 214. NO2Na/NH3( ) l?(a) NO2(b) NO2(c) NH2(d)None of these.15. NH2Na/liq. NH3?(a) NH2..(b) NO2(c) NH2(d)None of these.16. CH2 5Na/liq. NH3?O3PhP3(a) OO HC H5 2 (b) OOHH(c)Both (a) and (b).(d)None of these.17. NCH3Br/CCl2 4Major product(a) NCH3Br+Br(b) NBrCH3Br(c)No attack as no stable product formation is possible.(d)None of these.28 CHEMISTRY TODAY | FEBRUARY 1518.CH CH NO2H , Pd2alcohol?(a) CH CH NO2 2 2(b) CH CH NH2 2 2(c)CH CH NH NH2 2(d)Noneoftheseasdoublebondisin conjugation with the ring.19. OH , Pd/C2alcohol?(a) (b) (c) OH (d) O20. OOHBr2NaHCO3?(a) OOBr(b) BrCOONa (c) COONaBrCOONa(d)None of these.21. + H C CH CH2OCyclopenta-1,3-dieneMajor product = ?(a) CH CHCHO2 2(b) CHO(c) CH2CH2C O(d)None of these.22.Identify E in the given reaction sequence. HClCH (1 mole)2PdDAl O2 3400CECH COCH3 3NaNH2AHC CHB(a)H CC CH CH2 2CH3(b)CH CH CH CH CH3 2 2 2 3(Al2O3 has nothing to do)(c)CH CH CH C CH3 2CH3(d)None of these.23.Fromthefollowingsetofcompoundshow many will give the positive iodoform test?acetophenone, pentanal, 3-pentanone, ethanol, 2-butanol,ethanal,3-pentanol,phenacyl iodide(a)3(b)4(c)5(d)624. CH3CH3PhCOH3Major product(a) O OCH3CH3 (b) CH3OCH3(c) OCH3CH3(d)None of these.25. D2PtA ;H2PtB(a)A and B both are syn products.(b)A is anti but B is syn product.(c)BissynbutAisnotpossiblewithout heat.(d)A is syn, without heat B is also syn.CHEMISTRY TODAY| FEBRUARY 15 2926. BrNO2NO2+N H?Identify the product.(a) BrNO2NO2N (b) NO2NO2N(c) NO2NO2N (d)No reaction due to steric hindrance.27. SO H3BrFKSHX; = ? X(a) SOH3SHF (b) SOH3BrSH (c) NO2SHSH (d)SHBrF28. OC H2 5BrNaNH2Whichofthefollowingbestdescribesthe major product and nature of the reaction?(a) OCH2 5NH2; elimination-addition(b) OCH2 5NH2; addition-elimination(c) OC H2 5Br; cine substitutionH N2(d) OCH2 5; elimination-substitutionNH229. OHCHOconc. HNO3conc. H SO2 4?(Major)(a) OHCHONO2(b) OHCHOON2(c) OHCHOON2 (d) OHCHONO230. OHCHOconc. HNO3conc. H SO2 4?(Major)30 CHEMISTRY TODAY | FEBRUARY 15(a) OHCHONO2 (b) OHCHO ON2(c) OHCHOON2(d)None of these.31. NO2+?(a) NO2(b) NO2(c) NO2(d)Both (b) and (c).32. ClClfumingH SO2 4?(Major)(a) ClClSOH3(b) ClClSOH3(c) ClClSOH3SOH3(d)None of these.33. Br /FeBr2 3?(a)Br(b) Br Br(c) Br(d)None of these.nnCHEMISTRY TODAY| FEBRUARY 15 31Maximize your chance of success, and highrankinJEE(MainandAdvanced) /BITSATby reading this column. This speciallydesignedcolumnisupdatedyear after yearby a panel of highly qualified teachingexperts well-tuned to the requirements ofthese EntranceTests.UNIT-8Biomolecules|Polymers|Chemistry in Everyday LifeBIOMOLECULESlCarbohydrateslProteinslVitaminslNucleic AcidsTIPS TO REMEMBERCARBOHYDRATESCarbohydrates are optically active polyhydroxyaldehydesorketonesorthecompoundsthat canbebrokendownorhydrolysedinto polyhydroxy aldehydes or ketones.Tese are referred to as saccharides becauseofsweettasteofthesimplermembersof the class.Reducingsugars: Containfreealdehydicor ketonicgroupsandreduceFehlingssolution and Tollens reagent.Allmonosaccharidesanddisaccharideshavingfreealdehydicorketonicgroups arereducingsugars.e.g.,maltoseand lactose.Non-reducingsugars: Donothavefree aldehydic or ketonic groups and do not reduce Fehlings solution and Tollens reagent.In disaccharides, if the reducing groups ofmonosaccharides, i.e. aldehydic or ketonic groups are bonded, they are non-reducing in nature. e.g., sucrose.Allpolysaccharidesarenon-reducinginnature. e.g., cellulose, starch, glycogen etc.Depending on the number of products obtainedonhydrolysis,carbohydratesaredividedinto three major classes:Monosaccharides: (CH 2O)n, n = 3-7Oligosaccharides: (C 6H10O5)n, n = 210Polysaccharides: (C 6H10O5)n, n = 100 3000MonosaccharidesMonosaccharideswhichcontainanaldehydegroup(CHO)arecalledaldosesandthose which contain a keto group ( CO) are called ketoses.Teyarefurtherclassifedastrioses,tetroses,etc.dependinguponthenumber of carbon atoms they contain.O HC(CHOH)nCH OH2An aldoseCO(CHOH)nCH OH2CH OH2A ketoseTesimplestmonosaccharidesareglyceral- dehyde and dihydroxyacetone.Ofthesetwocompounds,onlyglyceral- dehyde contains a stereogenic centre. CHO*CHOHCH OH2Glyceraldehyde(An aldotriose)COCH OH2CH OH2Dihydroxyacetone(A ketotriose)32 CHEMISTRY TODAY | FEBRUARY 15Exceptketotriose(dihydroxyacetone),allaldoses and ketoses (monosaccharides) contain asymmetriccarbonatomsandareoptically active.Tesugarsaredividedintotwofamilies,theD-familyandL-familyonthebasis ofconfgurationofthesimplestsugar glyceraldehydewhichexistsintwoenantio-meric forms.CHOHC*OHCH OH2D-form (Glyceraldehyde)(OH group on the right sideof lowest asymmetric carbon)MirrorCHOHOC*HCH OH2L-form (Glyceraldehyde)(OH group on the left sideof lowest asymmetric carbon)Amonosaccharideisassigned D-confguration iftheOHgroupatthelastchiralcarbon atomliestowardsrighthandsidelikethatin D-(+)-glyceraldehyde.Ontheotherhand,itis assigned L-confguration if the OH group on the last chiral carbon atom lies on the lef hand side like that in L-()-glyceraldehyde.Allnaturallyoccurringmonosaccharidesbelong to D-series.KEYPOINTTe (+) and () signs only specify the directionofrotationoftheplanepolarizedlightbya particular enantiomer but it does not give any indicationofthearrangementofOHand H around the asymmetric carbon atom.GlucoseItisanaldohexosehavingformulaC 6H12O6. AlsocalledD-(+)-glucoseordextroseor grape sugar.Preparation Laboratorymethod: Fromsucrose(cane sugar)C12H22O11 + H2O H+ C6H12O6 + C6H12O6SucroseGlucoseFructoseCommercial method:From starch(C6H10O5)n + nH2O H /+393 K, 2-3 atmStarch or CellulosenC6H12O6 GlucosePhysical Properties Itisacolourless,crystallinesolid,meltsat146Candislesssweet(three-fourth) than cane sugar.Itisreadilysolubleinwater,sparinglysoluble in alcohol but insoluble in ether.Itisopticallyactiveandtheordinarynaturallyoccurringformis(+)-glucoseor dextro form. It shows mutarotation.Structure CH ( CH ) CH3 243n-HexaneNH OH2CHNOH(CHOH)4CH OH25(CH CO) O3 2HNO /Oxidation3Glucose oximeHCN(CHOH)4CH OH2CHOHCNGlucose cyanohydrin[O]/Br -water2 HI, (six carbon atoms arelinked in a straight chain)(confirms the presence ofa carbonyl group)(indicates aldehydic group)(confirms the presence offive OH groups)[indicates the presence ofa primary alcoholic(OH) group](confirms the presence ofa carbonyl group)(CHOH)4CHOCH OH2Glucose(CHOH)4CH OH2COOHGluconic acid(CHOCOCH )3 4CH OCOCH2 3CHOGlucose pentaacetate(CHOH)4COOHCOOHGlucaric acidor Saccharic acidor Glycaric acidCHEMISTRY TODAY| FEBRUARY 15 33Teexactspatialarrangementofdiferent OH groups was given by Fischer. CHOH OHHO HH OHH OHCHOH2D-(+)-GlucoseDespite having the aldehyde group, it doesnotgive2,4-DNPtest,Schifstestand itdoesnotformthehydrogensulphite addition product with NaHSO3.Tepentaacetateofitdoesnotreactwithhydroxylamineindicatingtheabsenceof free CHO group.Te above behaviour could not be explainedby the open chain structure. HCOHOH HH HOOH HHOCH OH2- -(+)-Glucopyranose D123456- -(+)-Glucopyranose DHCOH HH HOOH HHOCH OH2123456:OH:D-(+)-GlucoseHOCHOH HH HOOH HHOCH OH2123456Te cyclic structure of glucose is representedby Haworth structure. - -(+)-Glucopyranose DCHOH2HHOHHOHOHHHHOO654 13 2- -(+)-Glucopyranose DCHOH2HOHHHOHOHHHHOO654 13 2a andb-D-glucosehavediferentconf-gurationatanomeric(C-1)carbonatom, hencearecalledanomersandtheC-1 carbonatomiscalledanomericcarbon (glycosidic carbon).Tesixmemberedcyclicstructureofglucose is called pyranose structure.Chemical Reactions GlucoseDue toCHOgroupNa-Hg/HO2or NaBH4Fehling'ssolutionCuO + Gluconic2acid Red ppt.TollensreagentAgO22Ag +Gluconic acid Silvermirror5CHCOCl3Pyridine5PCl5CHO(CHCl)4CHCl2Pentachloroglucose(Glucose pentachloride)CHOH3dry HCl gasReductionOxidationD-SorbitolCHOH2(CHOH)4CHOH2Due toOHgroupCHO(CHOCOCH)34CHOCOCH2 3Glucose pentaacetate(a mixture of - and -) - -Methylglucoside DCOCH3H(CHOH)3CHCHOH2O +CCHO3H(CHOH)3CHCHOH2- -Methylglucoside DO34 CHEMISTRY TODAY | FEBRUARY 15KEYPOINTa and b-D-glucose are diastereomers.Anypairofdiastereomersthatdiferinconfgurationatonlyasingletetrahedral stereogeniccarbonarecalledepimers.e.g. D-glucose and D-mannose.Allmonosaccharidesandreducingdisacc- haridesreactwithexcessofphenylhydrazine to form crystalline osazones.Duringosazoneformation,onlyC 1andC2 areinvolved,therefore,allmonosaccharides which difer in confguration at C1 and C2 like glucose, mannose and fructose give the same osazone.Tests Reagents ObservationsWith little conc. H2SO4Charred residue of carbon.With dilute NaOH First yellow and then brown.Molischstest:Twodropsofalcoholicsolutionofa-naphthol+ 2 mL of glucose solution + conc. H2SO4 along the sides of test tube.Violetringatthejunctionof two liquids.Silver mirror test: With Tollens reagent Silver mirror appears.With Fehlings solution Red ppt. of Cu2O.SELF CHECK1.a-D-(+)-glucose and b-D-(+)-glucose are(a)enantiomers(b)conformers(c)epimers(d)anomers.(AIEEE 2008)2. Te term anomers of glucose refers to(a)isomersofglucosethatdiferin confgurationsatcarbonsoneandfour (C-1 and C-4)(b)a mixture of (D)-glucose and (L)-glucose(c)enantiomers of glucose(d)isomersofglucosethatdiferin confguration at carbon one (C-1).(AIEEE 2006)FructoseIt is a ketohexose having formula C 6H12O6. Also called laevulose or fruit sugar.Preparation From sucrose (cane sugar) C12H22O11 + H2O dil. H SO2 4 Cane sugarC6H12O6+C6H12O6 (Dextrorotatory)D-GlucoseD-Fructose(Dextrorotatory)(Laevorotatory)Te solution containing equimolar mixture ofD-(+)-glucoseandD-()-fructoseis called invert sugar and the process is known as inversion.From inulin (C6H10O5)n + nH2O dil. H SO2 4 nC6H12O6 InulinFructosePhysical Properties Teanhydrousfructoseisacolourless,crystalline compound, melts at 102 C.Itissolubleinwaterbutinsolubleinbenzene and ether.It is the sweetest of all sugars. Its solution is laevorotatory. Like glucose, it also shows mutarotation. Structure Onthebasisofitsreactions,itwasfoundtocontainaketonicfunctionalgroupat C-2 atom and six carbon atoms in straight chainasinthecaseofglucose.Itbelongs toD-seriesandisappropriatelywrittenas D-()-fructose.Itsopenchainstructureis as shown: CH OH2COHO HH OHH OHCH OH2123456D-()-FructoseCHEMISTRY TODAY| FEBRUARY 15 35It also exists in two cyclic forms which areobtained by the addition of OH at C-5 to theCOgroup.Tering,thusformed isafvememberedringandisnamedas furanose. HOH CCOH2H HOOH HHOCH OH2234561- -()-Fructofuranose DHOCCH OH2H HOOH HHOCH OH2234561- -()-Fructofuranose DTecyclicstructuresoftwoanomersoffructosearerepresentedbyHaworth structures.- -()-Fructofuranose DCHOH2OHHOHHOHHO654132HOHC2- -()-Fructofuranose DOHCHOH2HOHHOHHO654132HOHC2 Mutarotation Glucoseexistsintwoisomericforms, i.e., a-D-glucose(specifcrotation=+111)and b-D-glucose (specifc rotation = + 19.2).However, when aqueous solution of eitherofthesetwoformsisallowedtostand,it gets converted into an equilibrium mixture of both the a- and the b-forms with a small amount of the open chain form. As a result of this equilibrium, the specifcrotationofafreshlypreparedsolutionof a-D-glucose decreases from +111 to +52.7 whilethatofb-D-glucoseincreasesfrom +19.2 to +52.7.a-D-Glucose Equilibrium b-D-Glucosemixture[a]D = +111[a]D = + 52.7[a]D = +19.2Tischangeinspecifcrotationofanopticallyactivecompoundwithtimetoan equilibrium value is called mutarotation.Allmonosaccharidesandreducingdisaccharides undergo mutarotation. Fructose also undergoes mutarotation. a-D-Fructose Equilibrium b-D-Fructosemixture[a]D = 21[a]D = 92[a]D = 133KEYPOINTWhen glucose is treated with a dilute solutionofanalkali,itformsanequilibriummixture of D-glucose, D-fructose and D-mannose.Tis type of reaction is called Lobry de Bruynvan Ekenstein transformation and occurs via 1, 2-enolization.It is because of this, fructose reduces Tollensreagent and Fehlings solution although it does not contain any CHO group.HCOH OHHO HH OHH OHCH OH2OHH O2HO HH OHH OHCH OH2HCO:COHHO HH OHH OHCH OH2HCOCOHD-GlucoseEnolate ionHCOHO HHO HH OHH OHCH OH2D-MannoseH O2OHH OOH2C OH H2COHO HH OHH OHCH OH2D-Fructose EnediolHO HH OHH OHCH OH2HCOHCOHTautome-rizationOligosaccharidesDependingonthenumberofmonosaccharideunitsobtainedonhydrolysis,oligosaccharides aredividedintodisaccharides,trisaccharides, tetrasaccharides, etc.DisaccharidesDisaccharidesareformedwhentwomonosaccharidesarejoinedtogetherbyan oxide linkage (glycosidic linkage) formed by the loss of a water molecule.36 CHEMISTRY TODAY | FEBRUARY 15Sucrose (+)-Sucrose[ ] = + 66.5 DInvert sugar-(+)-Glucose [ ] = + 52.7 and D D-()-Fructose [ ] = 92.4 D DC H O + H O12 22 11( ) 2 sHydrolysisC H O + C H O6 12 6( ) 6 12 6( ) aq aqStructure - -Glucose DCHOH2HHHOHOHHHHOO654 13 2- -Fructose DHCHOH2HOHHOHO654132HOHC2OGlycosidiclinkageNature: Non-reducing sugar, dextrorotatoryMaltose 2(C6H10O5)n + nH2O HydrolysisDiastaseStarchnC12H22O11MaltoseStructure 21CHOH2OHHHOHHHOHO- -Glucose D(Non-reducing unit)O3456HH21CHOH2OHHHOHHHO- -Glucose D(Reducing unit)3456OH1,4- -Glycosidic linkageNature: Reducing sugar, dextrorotatory Lactose (+)-LactoseC H O + HO12 22 11( ) 2 sHydrolysisLactaseD-(+)-Glucose D-(+)-GalactoseCH O + CH O6 12 6( ) 6 12 6( ) aq aqStructure 21CHOH2OHHHOHHOHHO- -Galactose D(Non-reducing unit)O3456OHH21CHOH2OHHHOHHHO- -Glucose D(Reducing unit)3456HNature: Reducing sugar, epimeric in naturePolysaccharidesTey mainly act as the food storage or structuralmaterials.Tey are non-reducing in nature due to absenceof free aldehydic or ketonic groups.e.g., starch, cellulose, glycogen, gum etc.StarchIt is a polymer of a-D-glucose. Amylose21CHOH2OHHHOHHHO3456HOOH21CHOH2OHHHOHHHO3456OIt is water soluble.It constitutes about 15-20% of starch.It is a long unbranched chain. AmylopectinIt is insoluble in water.It constitutes about 80-85% of starch.Itconsistsofalargenumberofshort chainseachcontaining20-25glucose unitsjoinedthrough1,4-a-glycosidic linkages.Tebranchingoccursby 1,6-a-glycosidic linkage.CelluloseIt is a polymer of b-D-glucose.21CHOH2OHHHOHHHO3456HOOH21CHOH2OHHHOHHHO3456OnItisinsolubleinwaterandinmostofthe organic solvents.It is a linear polymer.CHEMISTRY TODAY| FEBRUARY 15 37KEYPOINTStarchandcellulosearethemainstoragepolysaccharidesofplants.Celluloseisthe major constituent of the cell wall in plants.Glycogenisananimalstarch.Itisamajorconstituentofliver,musclesandbrain.Itis also present in fungi and yeast.Likeamylopectin,glycogenisabranchedpolymerofa-D-glucose;infactitismore highly branched than amylopectin.PROTEINSProteins are biologically important compounds. Teyarecondensationpolymers(polyamides)madeupofdiferentsimplemonomericunits called a-amino acids.Proteins Hydrolysis Peptides Hydrolysis

a-Amino acidsAminoacidsarethebifunctionalmoleculeswithbothacidiccarboxylicgroup(COOH) and basic amino group (NH2).In a-aminoacids,theamino(NH2)group isata-positionw.r.t.carboxylic(COOH) group.i.e.,bothaminoandcarboxylicgroups are attached to the same carbon atom.OHONH2RAn -amino acid is a side chain at the carbon that R determines the identity of the amino acidName of amino acidStructure of R Tree letter symbolAmino acids with non-polar side chain Glycine H GlyAlanine CH3Ala*Valine CH(CH3)2Val*Leucine CH2CH(CH3)2Leu*Isoleucine CHCH CH2 3CH3Ile*Phenylalanine CH2C6H5PheProlineHN COOHH ProAminoacidswithpolarbutneutralsidechain*Tryptophan CH2HNTrpSerine CH2OH Ser*Treonine CH(OH)CH3TrTyrosine CH2C6H4OH(p) TyrCysteine CH2SH Cys*Methionine CH2CH2SCH3MetAsparagine CH2CONH2AsnGlutamine CH2CH2CONH2GlnAmino acids with acidic side chain Aspartic acid CH2COOH AspGlutamic acid CH2CH2COOH GluAmino acids with basic side chain *Lysine (CH2)4NH2Lys*Arginine (CH ) NHCNH2 3 2NHArg*HistidineNCH2NHHis*Essential amino acidsClassifcation of Amino AcidsDepending upon the relative number of amino(NH2) and carboxyl (COOH) groups.No. of COOH groups = No. of NH groups2, Glycine, Alanine, Valine e.g.AcidicNo. of COOH groups > No. of NH groups2, Aspartic acid, Asparagine, Glutamic acid e.g.BasicNo. of NH groups > No. of COOH groups2, Lysine, Arginine, Histidine e.g.Neutral38 CHEMISTRY TODAY | FEBRUARY 15On the basis of their synthesis: Cannot be synthesisedinthe body and must beobtainedthroughdiet.e.g. valine, leucine,l ys i ne, i s ol euci ne,arginine, etc.Whi c h c a n besynthesised in thebody.e.g. glycine, alanine,glutamicacid, asparticacid, etc.Non-essentialamino acidsEssentialamino acidsKEYPOINTWiththeexceptionofglycine,almostallnaturallyoccurringaminoacidshavethe L-confguration at the a-carbon.COOHH N C H2RAn - -amino acid L Properties Aminoacidsarecolourless,crystallinesubstances having sweet taste.Teymeltwithdecompositionathighertemperature (more than 200 C).Teyaresolubleinwaterbutinsolubleinorganic solvents.Exceptglycine,allthe a-aminoacidsare opticallyactiveandhaveanasymmetric carbon atom.In aqueoussolution, the carboxylic groupcanloseaprotonandaminogroupcan acceptaprotongivingrisetoadipolar ionknownaszwitterion.Tisisneutral butcontainsbothpositiveandnegative charges. R CHCOH:NH2OR CHCO+3NHOZwitter ionTerefore,aminoacidsareamphotericin nature. DependingonthepHofthesolution,theaminoacidcandonateoracceptproton. Intheacidicmedium,COOionofthe zwitterionacceptsaprotontoformthe cation while in the basic medium, N+H3 ion loses a proton to form the anion. R CHCO(in acidic solution)+3NHOHH+OR CHCO+3NHOH(in alkaline solution)R CHCONH2OOHH+In acidic solution (low pH), the positive ionmoves towards cathode (exists as cation).Inbasicsolution(highpH),thenegativeion moves towards anode (exists as anion).Te zwitter ion does not move towards anyof the electrodes (neutral dipolar ion).TeintermediatepHatwhichtheaminoacidshowsnotendencytomigrate towards any of the electrodes and exists in equilibrium when placed in an electric feld is known as isoelectric point.SELF CHECK3.Whichoneofthefollowingstatementsis correct?(a)All amino acids are optically active.(b)All amino acids except glycine are optically active.(c)Allaminoacidsexceptglutamicacidare optically active.(d)Allaminoacidsexceptlysineareoptically active.(AIEEE 2012)Formation of ProteinsProteinsareformedbyjoiningthecarboxylgroup of one amino acid to the amino group of another amino acid.Tebondformedbetweentwoaminoacidsbytheeliminationofawatermoleculeiscalleda peptide linkage or peptide bond. CHEMISTRY TODAY| FEBRUARY 15 39Teproductsformedbythelinkingofaminoacids by peptide linkage are known as peptides.Peptidescontaining2-10aminoacidsarecalled oligopeptides.Peptidescontainingmorethantenaminoacids are known as polypeptides. R, R, R may be same or diferent.Apolypeptidewithmorethanhundredamino acid residues, having molecular mass higher than 10,000 u is called a protein.KEYPOINTEachmoleculeofagivenproteinhasthesamesequenceoftheaminoacidsalongits polypeptide chain.Change of even one amino acid can drasticallychangethepropertiesofentireprotein molecule.ClassifcationofProteinsOn the basis of molecular structure, proteins areclassifed as fbrous and globular proteins. Globular proteinsGlobular proteins results when the polypeptidechains coil around to give three dimensionalspherical shape. These are soluble in water,, insulinandalbumin. e.g.In fibrous proteins, polypeptide chains areparallel and are held together by hydrogen anddisulphide bonds. These are insoluble in water,e.g., keratinandmyosin.Fibrous proteinsPrimarystructureofproteins: Itreferstothe number and sequence of the amino acids in its polypeptide chains. R3NHOOR2NHNHOOR4R1R5NHNHOR R1 5 may be any of the possible side chainsSecondarystructureofproteins: Te arrangementofpolypeptidechainsassumed asaresultofhydrogenbondingiscalledthe secondary structure of proteins.Telinkageorbondsinvolvedinthesecondarystructureformationare hydrogen bonds and disulphide bonds.It tells about the shape or confguration ofthe molecule.Dependingonthesizeofthe Rgroup, secondarystructureofproteinsisoftwo types:a-Helix b-Pleated sheetItisformedwhenthe chain of a-amino acidscoilsasaright handedscrewwith thesidechains projectingoutward fromthecoiled backbone. Itisformedwhenthepolypeptide chains are arrangedsidebyside inazig-zagmanner withalternateR groupsonthesame side.Tecoilisstabilizedbyintramolecular hydrogenbonds betweencarbonyl oxygenoffrst amino acid to amide nitrogenoffourth amino acid.Itisstabilizedbyintermolecular hydro-genbondsbetween thecarbonyloxygens andamidehydrogens oftwoormore adjacentpolypeptide chains. Suchproteinsareelastic,i.e.,theycan be stretched.Tesesheetscanslideover each other. e.g. myosin in nucleus andkeratininhair, wool,nails,claws, horns, feathers.e.g. silkfbroinisrich in b-pleated sheets.Itisformedif R groups are larger.Itisformedif R groups are smaller.Individualpolypeptidechains40 CHEMISTRY TODAY | FEBRUARY 15 SELF CHECK4.Te secondary structure of a protein refers to(a)fxedconfgurationofthepolypeptide backbone(b)a-helical backbone(c)hydrophobic interactions(d)sequence of a-amino acids.(AIEEE 2007)Tertiarystructureofproteins: Itrefersto thedefnitegeometricpatterninwhichthe entireproteinmoleculefoldsupinthethree dimensional space to produce a specifc shape.Furtherfolding,twistingandbendingofsecondarystructureresultsintertiary structure of proteins.Te bonds responsible for such interactionare as follows:Hydrophobic interactionsHydrogen bondsIonic interactionsvan der Waals forcesDisulphide bondsTese are of two types: Tertiary structure of fbrous protein has samesecondary(a-helixorb-pleated) structurethroughoutthelengthofthe protein.Tertiarystructureofglobularprotein doesnothavethesamesecondary structurethroughoutthelengthofthe molecule.Partsofthemoleculemay havea-helicalstructure,whilethe otherpartmayhaveb-pleatedsheet structure.Quaternarystructureofproteins: Someof theproteinsarecomposedoftwoormore polypeptidechainsreferredtoassub-units. Te spatial arrangement of these sub-units with respecttoeachotherisknownasquaternary structure of proteins.Denaturationofproteins: Itinvolvesirrever-sibleprecipitationofproteins.Tecomplex threedimensionalstructureofproteins changes by change in pH, temperature, presence of salts or certain chemical compounds. Denaturationdoesnotchangeprimarystructure but changes secondary and tertiary structuresofproteinse.g.,coagulationof albumin present in white part of egg when egg is boiled.It may be reversible or irreversible. EnzymesTe enzymes are biocatalysts produced by livingcellswhichcatalysebiochemicalreactionsin living organisms. Chemically, they are naturally occurring simple or conjugated proteins.Properties Enzymes are needed in very small amount.Tey reduce magnitude of activation energy. Tey are highly specifc. Tey work at specifc pH. Tey work well at moderate temperature. Importance Teyplayavitalroleinlivingorganismsas they catalyse many biological processes.Enzyme defciency causes diseases e.g., the defciencyofphenylalaninehydroxylase enzymecausesphenylketoneurea(PKU) andthedefciencyoftyrosinasecauses albinism.Teyareusedfortheproductionofbeer,wine, syrup and cheese etc.VITAMINSTesearecomplexorganicmoleculeswhichcannotbeproducedbythebodyandmustbe suppliedinsmallamountsindiettocarryout essential metabolic reactions which are required fornormalgrowthandmaintenanceofthe body.Classifcation Water soluble vitaminsFat soluble vitamins Soluble inwater. Must besuppliedregularlyindiet as theyareregularly excreted in urine (except vitaminB ). , Vitamin- B , B , B , B andC12 1 2 6 12e.g. Soluble infat andoils. Storedinliver andadiposetissues., Vitamin- A, D, EandK e.g.CHEMISTRY TODAY| FEBRUARY 15 41Vitamin name Chemical name Solubility Sources Defciency diseaseVitamin A Retinol or axerophtholFat Milk, butter, eggs, fsh, cod liveroil,greenvegetables, etc.Night-blindness, xerophthalmiaVitamin B1Tiamine Water Pulses,nuts,cereals(rice, wheat,etc.),ricebran, yeast,eggyolk,fruitsand green vegetables, etc.Beri-beri, loss of appetiteVitamin B2Ribofavin Water Milk, green vegetables, egg white,meat,liver,kidney, etc.Infammation of tongue, dermatitis, cheilosisVitamin B6Pyridoxine Water Ricebran,wholecereals (wheat,gram),yeast,fsh, meat, eggs, etc.Afects central nervous system, causes weakness, convulsions, insomnia and anaemiaVitamin H Biotin None Milk,yeast,liver,kidney, etc.DermatitisVitamin B12Cyanocobalamin Water Eggs,milk,liverofox, sheep, fsh, etc.Pernicious anaemiaVitamin C Ascorbic acid Water Citrusfruits,chillies, sprouted pulses, etc.Pyorrhea, scurvy (bleeding of gums)Vitamin D (amixtureof vitaminsD1 and D3)ErgocalciferolandcholecalciferolFat Butter, milk, eggs, fsh liver oil, liver and meat (Vitamin D3isproducedinskinin presence of sunlight).Rickets (bending of bones) and osteomalaciaVitamin E Tocopherol Fat Wheat germ oil, milk, nuts, peanutoil,cottonseedoil, eggs, fsh, etc.Loss of fertility in males, muscle degenerationVitamin K Phylloquinone Fat Leafyvegetableslike cabbage, spinach, etc.Haemorrhagesand lengthensthetimeof blood clottingKEYPOINTPlantscansynthesizeallvitaminsbutonlyafew are synthesized in animals.VitaminDisproducedintheskinbytheirradiationofergosterolpresentinthebody with ultraviolet light.Vitamin A is synthesized from carotenes. VitaminBcomplexandvitaminKaresynthesized by microorganisms present in the intestinal tract.NUCLEIC ACIDSNucleicacidsarecomplexcompoundsofcarbon,hydrogen,oxygen,nitrogenand phosphorus. Tey play an essential role in transmissionofthehereditarycharacteristicsand biosynthesis of proteins.Tey are polynucleotides. Nucleotidesarecomposedofthreeparts;pentosesugar,nitrogenousbaseand phosphate group.42 CHEMISTRY TODAY | FEBRUARY 15 NucleotidePentosesugarNitrogenousbasePhosphategroup (PO )43DeoxyriboseRiboseP OOOOPyrimidinesPurinesPentose sugar Deoxyribose: Ribose: KEYPOINTBoth D-riboseandD-2-deoxyribosedifer only at C-2 atom in the ring.Nitrogenousbase: Teseareheterocyclic organiccompoundshavingtwoormore nitrogen atoms in the ring.Pyrimidine derivatives: Purine derivatives: StructureNucleoside is formed by condensation of a basewith sugar at C-1 position.OHCN543 21SugarBaseN-GlycosidicbondBase-Sugar linkageH HHO HC2HOHNucleotide is formed when nucleoside is linkedtophosphoricacidatC-5positionofsugar moiety. OHCSugar HOP O CH2OOPhosphatePhosphate-Sugar-Base linkageNBaseN-Glycosidicbond5412 3OHHHNucleicacidisformedwhennucleotidesarejoinedtogetherbyphosphodiesterlinkages between5and3carbonatomsofpentose sugar. Twotypesofnucleicacids, viz,DNAand RNAaredistinguishedfromeachotherinthe following manner:CHEMISTRY TODAY| FEBRUARY 15 43Deoxyribonucleic acid (DNA)Components Ribonucleic acid (RNA)2-deoxy-D-() ribose Sugar D-() riboseCytosine and thymine Pyrimidine baseUracil and cytosineAdenine and guanine Purine base Adenine and guanineH3PO4Phosphoric acidH3PO4Double stranded a-helixStructure Single stranded a-helixPossible Replication Not possiblePrimarystructureofnucleicacid: Itinvolves thecombinationofthousandsofmolecules ofnucleotideswiththeeliminationofwater molecules.Secondary structure of nucleic acid:SecondarystructureofDNAconsistsoftwo polynucleotide chains, twisted about a common axis, but run in opposite direction to form a right handed helix.Tetwochainsarejoinedtogetherby specifchydrogenbondsA(Adenine) toT(Tymine)andG(Guanine)to C(Cytosine). Approximately there are ten nucleotide units in one turn of each strand and the backbone(consistingof2-deoxyribose and phosphate units) of each nucleotide liesoutsidethehelixofeachstrand, while the nitrogen bases in each strand lie in the centre of the helix.In secondary structure of RNA, helices arepresentwhichareonlysinglestranded. Sometimes they fold back on themselves to form a double helix structure.Chargafsrule: Amountofpurinebasesis always equal to that of pyrimidine bases. Purine base of one strand of DNA moleculepairswithpyrimidinebaseoftheother strand. Adenine(A)pairswiththymine(T)through two H-bonds (A T) and guanine (G)pairswithcytosine(C)throughthree H-bonds (G C).IncaseofRNA,adenine(A)pairswithuracil (U), (A U).Nucleic acids have two main functions: 1.Replication 2.Protein synthesisSELF CHECK5.Which one of the following bases is not present in DNA?(a)Tymine(b)Quinoline(c)Adenine(d)Cytosine(JEE Main 2014)6.Tepresenceorabsenceofhydroxygroupon which carbon atom of sugar diferentiates RNA and DNA?(a)1st(b)2nd(c)3rd(d)4th(AIEEE 2011)7.In both DNA and RNA, heterocyclic base and phosphate ester linkages are at(a)C5 and C2 respectively of the sugar molecule(b)C2 and C5 respectively of the sugar molecule(c)C1 and C5 respectively of the sugar molecule(d)C5 and C1 respectively of the sugar molecule.(AIEEE 2005)8.Te pyrimidine bases present in DNA are(a)cytosine and adenine (b)cytosine and guanine(c)cytosine and thymine (d)cytosine and uracil.(AIEEE 2006)KEYPOINTMutation is a chemical or physical change thataltersthesequenceofbasesinDNAstrands that can lead to the synthesis of proteins with altered a-amino acid sequence.Tesemutationsofenproveharmfulandgive rise to symptoms that cause diseases.44 CHEMISTRY TODAY | FEBRUARY 15POLYMERSlClassifcation of PolymerslMethods of PolymerizationlCopolymerizationlRubberlSome Important PolymersTIPS TO REMEMBERPolymersarethemacromolecules,whichareformedbyjoiningofrepeatingstructuralunits knownasmonomersandarelinkedtoeach otherbycovalentbonds.Tisprocessiscalled polymerization.Tere are two types of polymers, homopolymers(onlyonetypeofmonomers)andcopolymers (two or more types of monomers).CLASSIFICATION OF POLYMERSItdependsonsource,structure,modeofpolymerization,molecularforcesandtype ofmechanisminvolvedduringthegrowthof polymerization chain.Onthebasisofsource,theyarenatural,synthetic and semi-synthetic polymers.Onthebasisofstructure,theyarelinear,branchedchainandcross-linked polymers.Onthebasisofmodeofpolymerization,they are addition and condensation polymers.Onthebasisofmolecularforces,theyareelastomers,fbres,thermoplasticand thermosetting polymers.On the basis of type of mechanism involvedduring the growth of polymerization chain, theyarechaingrowthandstepgrowth polymers.METHODS OF POLYMERIZATIONChain growth addition polymerization It involves a series of reactions each of whichconsumes a reactive particle and produces anothersimilarone.Tereactiveparticles maybefreeradicalsorions(cationsor anions)towhichmonomers(alkenesor conjugateddienes)getaddedbyachain reaction.Dependinguponthereactiveparticlesformed,itisfurtherdividedintothree types:Free radical polymerizationCationic polymerizationAnionic polymerizationFree radical polymerization Initiators which generate free radicals on heating are dioxygen, benzoyl peroxide, acetyl peroxide, tert-butyl peroxide.Freeradicalthusformedaddstothe doublebondofmonomerandformsa newandlargefreeradical.Tisstepis chain initiating step.Repetitionofthisstepwithnew andlargerradicalsiscalledchain propagating step.Tegrowingfreeradicalchaingets terminated by reactions which consume these free radicals either by combination orbydisproportiontogetpolymeris called chain termination step.Cationic polymerization Monomerswithelectrondonating substituentsarepolymerizedbya cationicpolymerizationinitiatedby strongLewisacidssuchasBF3,AlCl3, H2SO4etc.inpresenceofatraceof water as initiator.H2SO4 H+ + HSO4H+ + CH2 CH2 CH3 CH2+CarbocationAnionic polymerization Monomerswithelectronwithdrawing substituentsarepolymerizedbyan anionicpolymerizationinitiatedby strongbasessuchasNa,KNH2or organometallic compounds. B: + CH CH2 2B CH CH2 2CarbanionSELF CHECK9.Te species which can best serve as an initiator for the cationic polymerization is(a)HNO3(b)AlCl3(c)BuLi(d)LiAlH4(AIEEE 2012)CHEMISTRY TODAY| FEBRUARY 15 45Step growth condensation polymerization Inthistypeofpolymerizationreactions,monomers are bifunctional and form bond withthelossofsimplemoleculeofwater, alcohol, ammonia, etc.Tedimerformed,alsocontainstwofunctional groups , thus undergoes a series of condensations in a stepwise manner and results in the formation of a high molecular mass condensation polymer.COPOLYMERIZATIONWhentwoormorediferentmonomersunitetogether to polymerize, the resulting product is called a copolymer and the process is termed as copolymerization.Tepropertiesofacopolymerareentirelydiferentfromaphysical mixtureofthetwoindividualpolymers. Copolymershavebetterphysicaland mechanical properties.Te properties could be changed by varyingthe amounts of each monomer.RUBBERIt is of two types: Natural rubber It is obtained as latex from rubber tree.It is highly elastic.It is cis-1,4-polyisoprene.All trans confguration occurs naturally as gutta-percha, which is non-elastic.Synthetic rubber Itisobtainedbypolymerizingcertain organiccompoundswhichmayhave propertiessimilartorubberandsome additional desirable properties. Most of these polymers are derived from butadienederivatives.Forexample, neoprene,buna-S,buna-N,thiokol, silicones, polyurethane rubber.Vulcanization of RubberVulcanizationisaprocessoftreatingnaturalrubber with sulphur and an appropriate additive atatemperaturerangeof373to415K,to modify its properties. On vulcanization sulphur formscross-linksatthereactivesitesofthe double bonds and gives mechanical strength to the rubber.Teextentofhardnessortoughness,however,dependsupontheamountofsulphuradded. Tus, about 5% sulphur is used for making tyre rubber, 20-25% sulphur for making ebonite and 30% sulphur for making battery case rubber.KEYPOINTNumber average molecular mass( ) MN MNni ii= W eight (mass) average molecular mass ( ) MN MN Mwi ii i= 2Polydispersity Index (PDI) = MMwnPolymerswhichareproducedbybiologicalsystemssuchasmicroorganisms,plants andanimalsandareessentialforlifeare biopolymers.Teycanalsobesynthesizedchemically.e.g.,starch,cellulose,proteins,nucleicacids, PHBV etc.Teyarebiodegradable e.g.,PHBV,poly (glycollicacid)poly(lacticacid)and nylon-2-nylon-6.46 CHEMISTRY TODAY | FEBRUARY 15SOME IMPORTANT POLYMERSPreparation of Addition HomopolymersPolyolefns Polymer Structure of monomer Structure of polymerPolythene CH2 CH2 Ethylene( CH2CH2 ) nPolypropylene CH3CH CH2 PropylenePolytetrafuoroethene (Tefon) (PTFE) CF2 CF2 Tetrafuoroethene( CF2CF2 ) nPolyacrylonitrile (Orlon) (PAN) CH2 CHCN Acrylonitrile(Vinyl cyanide)Polyvinyl chloride (PVC) CH2 CHCl Chloroethene (Vinyl chloride)Polystyrene (Styron)Polymethylmethacrylate (PMMA)MethylmethacrylatePolymonochlorotrifuoroethylene (PCTFE)Polydienes Polymer Structure of monomer Structure of polymerNatural rubberNeoprene (synthetic rubber)Gutta-perchaCHEMISTRY TODAY| FEBRUARY 15 4748 CHEMISTRY TODAY | FEBRUARY 15Preparation of Addition CopolymersPolydienes Polymer Structure of monomer Structure of polymerBuna-S(Styrene Butadiene Rubber) (SBR)CH2 CHCH CH2 1, 3-ButadieneBuna-N (Nitrile rubber)Preparation of Condensation HomopolymersPolyamidesPolymer Structure of monomer Structure of polymerNylon-6(Perlon-L)Polyesters Polymer Structure of monomer Structure of polymerPolyhydroxybutyrate (PHB)Your feedback will help us to serve you betterWe request Readers to send their views/suggestions. Te honest feedback given by you will help in improvement of your favourite magazine.E-mail your suggestions to : editor@mtg.inCHEMISTRY TODAY| FEBRUARY 15 49Preparation of Condensation CopolymersPolyamides Polymer Structure of monomer Structure of polymerNylon-6,6HOOC(CH2)4COOHAdipic acidH2N(CH2)6NH2HexamethylenediamineNylon-6, 10 HOOC(CH2)8COOH Sebacic acidH2N(CH2)6NH2HexamethylenediamineNylon-2, 6 H2NCH2COOH GlycineH2N(CH2)5COOH 6-Aminohexanoic acidPolyesters Polymer Structure of monomer Structure of polymerTerylene(Dacron)HOCH2CH2OHEthylene glycol (Ethane-1,2-diol) Glyptal(Alkyd resin)HOCH2CH2OHEthylene glycolPoly b-hydroxy butyrate-co-b-hydroxy valeratre (PHBV)Poly(glycollic acid)poly(lactic acid)(Dextron)HOCH2COOH Glycollic acid 52 CHEMISTRY TODAY | FEBRUARY 15Formaldehyde resins Phenol-formaldehyde resin (Bakelite)o-Hydroxymethylphenolp-Hydroxymethylphenol

Melamine-formaldehyde resin (Melmac)Urea-formaldehyde resinPolysulphide Tiokol[ CH2CH2SSSS] nClCH2CH2Cl Ethylene dichloride Na2S4Sodium tetrasulphideCHEMISTRY TODAY| FEBRUARY 15 53SELF CHECK10.Whichoneisclassifedasacondensation polymer?(a)Acrylonitrile(b)Dacron (c)Neoprene(d)Tefon(JEE Main 2014)11.Buna-N synthetic rubber is a copolymer of (a) ClH CCHCCH2 2andH2C CH CH CH2(b)H2C CH CH CH2 andH5C6CH CH2(c)H2C CH CN andH2C CH CH CH2(d)H2C CH CN and ClH CCHCCH2 2(AIEEE 2009)12.Whichofthefollowingisfullyfuorinated polymer?(a)Neoprene(b)Tefon(c)Tiokol(d)PVC (AIEEE 2005)CHEMISTRY IN EVERYDAY LIFElChemicals in MedicineslChemicals in FoodlCleansing AgentsTIPS TO REMEMBERCHEMICALS IN MEDICINESDrugsarelowmolecularmasschemicalswhichinteractwithmacromoleculartargets andproduceabiologicalresponse.Whenthe biologicalresponseistherapeuticanduseful, these chemicals are called medicines.Use of chemicals for therapeutic efect is calledchemotherapy.Drugs whichreduce or neutralise acidity.e.g. baking soda, metal hydroxides likeAl ( OH) , Mg( OH) , c i me t i di ne ,3 2ranitidine, lansoprazole, omeprazole.Drugs which are used for thet reat ment of al l ergi es. e. g.diphenylhydramine (benadryl),pheni rami ne mal eate (avi l ),chlorpheniramine(zeet).Drugs whichinhibit the actionorg r owt h of mi c r obe s . e . g .antibiotics, anti septics anddisinfectants..Drugs which kill or stop the growthof microorganisms, but are harmfulto living cells . 1%solution of e.gphenol, bleachingpowder, HO.2 2AntacidsDrugs which are produced by living cells and capable of inhibiting the life processes of micro-organisms. penicillin, erythromycin, tetracycline, etc. e.g.AntibioticsDrugs which are applied to the livingtissues such as wounds, cuts, ulcers anddiseased skin surfaces. furacin, e.g.soframycin, dettol.AntisepticsDrugs which are used for thetreatment of stress, fatigue, mildandsevere mental diseases.Narcotics: Heroin, pethidine.Sedatives: Valium, barbiturates.Antidepressants : Iproniazid, phenelzine.Hypnotics : Seconal, luminal, veronal.Non-hypnotics : Equanil, meprobamate, chlorodiazepoxide.TranquillizersDr ugs whi ch are us ed t o br i ngdown the body temperature duringhighfever.e.g. aspirin, phenacetinandparacetamol.AntipyreticsAntihistaminesDrugs whichrelieve pain.Non-narcotics : aspirin, paracetamol.Narcotics : morphine, codeine.AnalgesicsAntifertilityDrugsDrugs whichare usedtoreduce birthrates. . mifepristone. e.gDisinfectantsAntimicrobials54 CHEMISTRY TODAY | FEBRUARY 15KEYPOINTAnaestheticsarethedrugswhichproduceinsensibility to the vital functions of all types ofcellsespeciallyofnervoussystem.e.g. sodium pentothal.SELF CHECK13.Aspirin in known as(a)phenyl salicylate(b)acetyl salicylate(c)methyl salicylic acid(d)acetyl salicylic acid.(AIEEE 2012)14.Whichoneofthefollowingtypesofdrugs reduces fever?(a)Analgesic(b)Antipyretic(c)Antibiotic(d)Tranquilizer(AIEEE 2005)CHEMICALS IN FOODChemicals which are added to food to improveitskeepingqualities,appearance,taste,odour andnutritive(food)valuearecalledfood additives.Food PreservativesCompoundswhichareusedtoprotectfoodagainstbacteria,yeastsandmoulds.e.g.table salt, sugar, citric acid, sodium benzoate, salts of propionic acid, sorbic acid.Artifcial Sweetening AgentsCompoundswhichgivesweeteningefectandenhancecolourandfavouroffood.e.g. saccharin, aspartame, alitame.AntioxidantsCompounds which are used to prevent oxidationof fats in processed foods such as potato chips, biscuits,breakfastcereals,crackers,etc.e.g. butylated hydroxy anisole (BHA) and butylated hydroxy toluene (BHT).CLEANSING AGENTSSoapsTeyarethesodiumorpotassiumsaltsofsaturated and unsaturated long chain carboxylic acidscontaining12to18carbonatoms(fatty acids). e.g. salts of C15H31COOH (palmitic acid), C17H35COOH(stearicacid),C17H33COOH (oleic acid), C17H31COOH (linoleic acid), etc.Synthetic DetergentsTeyarethesodiumsaltsoflongchainalkylhydrogen sulphates or the sodium salts of long chain benzene sulphonic acids.Classifcation of detergents Anionicdetergents: Teseareoftwo types:Alkyl hydrogen sulphatesCH3(CH2)10CH2OSO3Na+Sodium laurylsulphateSodium alkyl benzene sulphonates CH3CH (CH) CH3 29SONa3+Sodium-2-dodecylbenzene sulphonate (SDS)Cationic detergents: Trimethylstearylammonium bromideCH3CH (CH ) CH NCH Br3 2 16 2 3+CH3Cetyltrimethylammonium chlorideCH3CH (CH ) NCH Cl3 2 15 3+CH3Non-ionic detergents: CH3(CH2)10CH2(OCH2CH2)8OHLauryl alcohol ethoxylateCH3(CH2)16COO(CH2CH2O)nCH2CH2OHPolyethyleneglycol stearateAdvantages of Synthetic Detergents over SoapsTesecanbeusedbothinsofandhardwaterwhereas ordinary soaps cannot be used in hard water.Teaqueoussolutionofdetergentsareneutralandhence,canbeusedforwashingalltypes offabricswithoutanydamage.Tesolutionof ordinarysoapisalkalineandthus,cannotbe used to wash delicate fabrics.CHEMISTRY TODAY| FEBRUARY 15 5556 CHEMISTRY TODAY | FEBRUARY 15Tesecanbeusedeveninacidicmediumastheyaresaltsofstrongacidsandarenot decomposedinacidicmediumwhereassoaps aredecomposedintocarboxylicacidsinacidic medium.Cleansing Action of Soaps and DetergentsTeorganicpartofanaturalsoap(polarmolecule) is negatively charged.Itshydrophilic(waterloving)carboxylategroup(COO)interactswithwater moleculesviaion-dipoleinteractionsand hydrogen bonding.Tehydrophobic(water-repelling)partofasoapmoleculewhichislong,non-polar hydrocarbon chain, does not interact with water molecules.Tehydrocarbonchainsareattractedtoeachotherbydispersionforcesand clustertogether,formingstructurescalled micelles.In these micelles, the carboxylate groups formanegativelychargedspherical surface,withthehydrocarbonchains inside the sphere.Becausetheyarenegativelycharged, soapmicellesrepeleachotherand remain dispersed in water.ANSWER KEYS (SELF CHECK)1.(d)2.(d)3.(b)4.(b)5.(b)6.(b)7.(c)8.(c)9.(b)10.(b) 11.(c)12.(b)13.(d)14.(b)1.Which of the following is correct statement?(a)Starch is a polymer of a-D-glucose.(b)Amylose is a component of cellulose.(c)Proteins are composed of only one type of amino acid.(d)Incyclicstructureoffructose,thereare four carbons and one oxygen atom.2.Naturalrubberandgutta-percharespectively are(a)trans-polychloroprene and cis-polychloroprene (b)both are cis-polyisoprene(c)both are trans-polyisoprene(d)cis-polyisoprene and trans-polyisoprene.3.Which set has diferent class of compounds?(a)Tranquillizers : equanil, heroin, valium(b)Antiseptics : bithional, dettol, boric acid(c)Analgesics : naproxen, morphine, aspirin(d)Bactericidal:penicillin,aminoglycosides, ofoxacin4.Which of the following amino acids is basic in nature?(a)Glutamine(b)Arginine(c)Serine (d)None of these5.Consider the following polymers :I.PolystyreneII.DacronIII.OrlonTey are classifed asIIIIII(a)chain-growth; step-growth; step-growth(b)chain-growth; chain-growth; step-growth(c)chain-growth; step-growth; chain-growth(d)step-growth; step-growth; chain-growthCHEMISTRY TODAY| FEBRUARY 15 576.Whichofthefollowingisnotusedasan antacid?(a)Magnesium hydroxide(b)Sodium carbonate(c)Sodium bicarbonate(d)Aluminium phosphate7.Tecorrectstatementaboutthefollowing disaccharide is (a)Ring(i)ispyranosewitha-glycosidic linkage.(b)Ring(i)isfuranosewitha-glycosidic linkage.(c)Ring(ii)isfuranosewitha-glycosidic linkage.(d)Ring(ii)ispyranosewithb-glycosidic linkage.8.Monomer of orlon is(a)H2C CH Cl(b)H2C CH C N(c) H CCHOCOCH2 3(d)F2C CF29.Whichofthefollowingpossessgermicidal properties?(a)Cationic detergents(b)Anionic detergents(c)Non-ionic detergents(d)None of these10.Twoisomericsugarsthatarecyclicandonly difer in the position of the OH group at the glycosidic carbon are called(a)enantiomers(b)mutarotators(c)anomers(d)epimers.11.Acrilanisahard,hornyandhighmelting material. Which of the following represents its structure?(a)CH CH2CN n(b) CH C2COOCH3nCH3(c) CH CH2COOCH2 5 n(d) CH CH2Cln12.Choose the correct statement.(a)Saccharin is 650 times sweeter than sugar.(b)Aspartame is 550 times sweeter than sugar.(c)Sucralose is 160 times sweeter than sugar.(d)Alitame is 2000 times sweeter than sugar.13.Considerthefollowingstatementsabout sucrose :I.Hydrolysisofsucrosewithdiluteacid yieldsanequimolarmixtureofD-glucose and D-fructose.II.Acid hydrolysis of sucrose is accompanied by a change in optical rotation.III.In sucrose, the glycosidic linkage is between C1 of glucose and C2 of fructose.IV.Aqueoussolutionofsucroseexhibits mutarotation.Whichofthestatementsgivenaboveare correct?(a)I, II and III(b)I and IV(c)II, III and IV(d)II and IV14.Tebestwaytopreparepolyisobutyleneis through(a)coordination polymerisation(b)cationic polymerisation(c)anionic polymerisation(d)free radical polymerisation.15.Which of the following is an example of liquid dishwashing detergent?(a)CH3(CH2)10CH2OSO3Na+(b)CH3(CH2)16COO(CH2CH2O)nCH2CH2OH(c) CH3SO3Na+(d)CH (CH ) NCH Br3 2 15 3CH3CH3+58 CHEMISTRY TODAY | FEBRUARY 1516.Which of the following represents the anomer of the compound shown?H HOHOCH2H OHHHO OH(a) OHHOHOCH2H OHHH OH (b) OHOHOHOHC2HOHHH H(c) H HOHOCH2H HOHHO OH(d)None of these17.Arrange the given polymers in increasing order of their intermolecular forces.A = Nylon-6; B = Neoprene; C = PVC(a)A < B < C(b)C < B < A(c)B < C < A(d)A < C < B18.Anantibioticcontainsnitrogroupattachedto aromatic nucleus in its structure. It is(a)penicillin(b)streptomycin(c)tetracycline(d)chloramphenicol.19.TwosamplesofDNA,IandIIhavemelting points340Kand350Krespectively.Tisis because(a)II has more GC content than I(b)I has more GC content than II(c)II has more AT content than I(d)both have same AT content.20.Arrangethefollowingmonomersinorder ofdecreasingabilitytoundergocationic polymerisation.I.CH2 CH C6H4(NO2)II.CH2 CH C6H4(CH3)III.CH2 CH C6H4(OCH3)(a)I > II > III(b)III > II > I(c)II > I > III(d)I > III > II21. OHCH3CHCOCl3PyridineXKMnO4YTefnalproductYisamedicine.Whichof the following is incorrect regarding Y?(a)Ithasanalgesicaswellasantipyretic properties.(b)It helps to prevent heart attack.(c)It has anti-blood clotting action.(d)It suppresses the gastric anomalies.22.Periodicacidsplitsglucoseandfructoseinto formic acid and formaldehyde. Ratio of formic acidtoformaldehydeobtainedfromglucose and fructose respectively are(a)4/2 and 4/2(b)5/1 and 5/1(c)5/1 and 3/2(d)none of these.23.Whichofthefollowingpairsofmonomers form biodegradable polymer?I.3-Hydroxybutanoic acid +3-hydroxypentanoic acidII.Glycine + e-aminocaproic acidIII.Ethylene glycol + phthalic acidIV.Caprolactam(a)I, II only(b)II, III only(c)I, II and III only(d)II, III and IV only24.Whichofthefollowingdrugcombinationsis not correct?(a)Phenacetin-antipyretic(b)Chloramphenicol-broad spectrum antibiotic(c)Equanil-sedative(d)Bithional-tranquillizer25.Whichofthefollowingisnotana-amino acid?(a)Cysteine(b)Proline(c)Trypsin(d)Serine26.MatchthepolymersgiveninColumnIwith their commercial names given in Column II.CHEMISTRY TODAY| FEBRUARY 15 59Column I Column IIA. Polyesterofethyleneglycol and phthalic acid1. NovolacB. Copolymer of 1,3-butadiene and styrene2. GlyptalC. Phenolandformaldehyde resin3. Buna-SD. Polyesterofethyleneglycol and terephthalic acid4. Buna-NE. Copolymer of 1, 3-butadiene and acrylonitrile5. DacronABCDE(a)43215(b)23154(c)21345(d)2135427.Salol can be used as an(a)antiseptic(b)antipyretic(c)both (a) and (b)(d)none of these.28.Chargafs rule states that in an organism(a)amountofadenine(A)isequaltothatof thymine (T) and amount of guanine (G) is equal to that of cytosine (C) (b)amountofadenine(A)isequaltothatof guanine (G) and amount of thymine (T) is equal to that of cytosine (C)(c)amountofadenine(A)isequaltothatof cytosine (C) and amount of thymine (T) is equal to that of guanine (G)(d)amounts of all bases are equal.29.Polymer used in bullet proof glass is(a)PMMA(b)Lexan(c)Nomex(d)Kevlar.30.In a polymer sample, 30% of molecules have a molecular mass of 20,000 u, 30% have 30,000 u and rest 40,000 u. What is the average molecular mass of the polymer?(a)29,000 u(b)30,000 u(c)31,000 u(d)32,000 uSOLUTIONS1.(a)2.(d) : Naturalrubberiscis-polyisoprenewhile gutta-percha is trans-polyisoprene.3.(a) : Heroin is not a tranquillizer, it is a narcotic analgesic.4.(b) : ArginineH NCH(CH ) NHCNH2 2 2 2NH COOHa-Amino acids like arginine which contain two NH2groupsandoneCOOHgroupare called basic amino acids.5.(c)6.(b)7.(a) : Tedisaccharideissucrose,with a-glycosidiclinkagebetweenC1ofglucose present in the pyranose form (ring i) and C2 of fructose present in the furanose form (ring ii).8.(b)9.(a) : Cationicdetergentsarequaternary ammoniumsaltscontainingoneormorelong chainalkylgroupsandpossessinggermicidal properties.10.(c)11.(a) : Acrilan is a polymer of acrylonitrile.12.(d) : Saccharin is 550 times sweeter than sugar, aspartameis100timessweeterthansugar. Sucralose is 600 times sweeter than sugar.13.(a)14.(b) : Since3carbocationsaremoststable,the bestwaytoobtainpolyisobutyleneisthrough cationicpolymerisationinthepresenceof Lewis acid or protonic acid.CH C(CH)2 32CH C(CH)3 32H+ +193 K2-Methylpropene(Isobutylene)nCH C(CH)2 3 2CH3CH C2CH3 nPolyisobutylene60 CHEMISTRY TODAY | FEBRUARY 1515.(b) : Liquid dishwashing detergents are of non-ionic type.16.(c)17.(c): Neopreneisanelastomer,thushas weakestintermolecularforces.Nylon-6isa fbre,thushasstrongintermolecularforces likeH-bonding.PVCisathermoplastic polymer,thustheintermolecularforces presentinPVCareinbetweenthoseof elastomersandfbres.Tus,theorderof intermolecular forces of these polymers isNeoprene < PVC < Nylon-618.(d) : Amongthegivenantibiotics,only chloramphenicolcontainsanitrogroup attached to aromatic ring. O N2CHCHCH OH2NHCOCHCl2ChloramphenicolOH19.(a) : SinceGCbasepairhasthreeH-bondsso it is more stable than AT base pair having two H-bonds. As DNA II has higher melting point than DNA I thus, it has more GC content than sample I.20.(b) : Electronreleasinggroupssuchas CH3, OCH3 activate the monomer towards cationicpolymerisationasthesegroups providestabilitytothecarbocationformed. Tus, the correct order isCH2 CH C6H4(OCH3) >(III)CH2 CH C6H4(CH3) >(II)CH2 CH C6H4(NO2)(I)21.(d) : OHCH3CHCOCl3OCOCH3CH3KMnO4OCOCH3COOHAcetylsalicylic acid (Aspirin)Pyridine( ) X( ) YAspirin acts as a gastric irritant.22.(c):CHOHHOHHOHHOHOHCHOH2123456D-Glucose5HIO45HCOOH + HCHO1-5 6CH OH2HOHHOHOHOHCH OH2123456D-Fructose5HIO43HCOOH + 2HCHO + CO23-5 1+6 223.(a) : PHBVandnylon-2-nylon-6are biodegradable polymers.nCH CHCH COH +3 2OOH3-Hydroxybutanoic acidnCH CH CHCH COH3 2 2O OH3-Hydroxypentanoic acidOCHCH COCHCH C2 2nCH3O O CH CH2 3PHBVnH2NCH2COOH + nH2N(CH2)5COOH Glycinee-Aminocaproic acidNylon-2-nylon-6HNCH CONH(CH ) C2 2 5 nO24.(d) : Bithional is an antiseptic.25.(c)26.(b)27.(a)28.(a) : AccordingtoChargafsrule,thebase composition in DNA varied from one organism toanotherbutinallcases,theamount(in moles) of adenine was equal to that of thymine (A = T) and that of cytosine was equal to that of guanine (C = G).29.(b)30.(c): Average molecular mass,Mn = + + + +30 20 000 30 30 000 40 40 00030 30 40, , ,= 31,000 unnCHEMISTRY TODAY| FEBRUARY 15 611.Namethepolymerusedforinsulationof electrical wires.2.What type of drug is chloramphenicol?3.Whatisthediferencebetweennylon-6and nylon-6,6?4.Nametheantibioticsupposedtobetoxic towards certain strains of cancer cells.5.Whichtypeofcompoundsarepresentin antifertility drugs?6.Give reason for the following :(i)Whileantacidandantiallergicdrugs interferewiththefunctionofhistamines, they do not interfere with the function of each other.(ii)Overdoses of aspirin and its use on empty stomach should be avoided.7.Classifythefollowingasadditionand condensation polymers.(i)Terylene(ii)Bakelite(iii)Polyvinyl chloride(iv)PolytheneAlso write their monomers.8.(i) Howdoantisepticsdiferfrom disinfectants? Give one example of each.(ii)Nameacompoundwhichcanbeusedas an antiseptic as well as disinfectant.9.(i) Howdoesvulcanizationchangethe properties of natural rubber?(ii)Why are the numbers 66 and 6 put in the names of nylon-6, 6 and nylon-6?10.Write the names and the structures of monomers of following polymers :(i)Natural rubber(ii)PHBVORDistinguishbetweenthetermshomopolymer and copolymer and give an example of each.11.Whataredetergents?Givetheschemeof classifcationofsyntheticdetergents.Whyare they preferred over soaps?GENERAL INSTRUCTIONS(i)All questions are compulsory.(ii)Question numbers 1 to 5 are very short-answer questions and carry 1 mark each.(iii)Question numbers 6 to 10 are short-answer questions and carry 2 marks each.(iv)Question numbers 11 to 22 are also short-answer questions and carry 3 marks each.(v)Question number 23 is value based question and carries 4 marks.(vi)Question numbers 24 to 26 are long-answer questions and carry 5 marks each.(vii)Use Log Tables, if necessary. Use of calculator is not allowed.Time : 3 hrs. Marks : 70BOARDCB SECHAPTERWISE PRACTICE PAPER2015Polymers, Chemistry in Everyday LifeSeries-962 CHEMISTRY TODAY | FEBRUARY 1512.(i) Explain the term, target molecules or drug targets as used in medicinal chemistry.(ii)Name the macromolecules that are chosen as drug targets.(iii)Diferentiatebetweenagonistsand antagonists.13.Howarepolymersclassifedintodiferent categories on the basis of intermolecular forces? Give one example of a polymer of each of these categories.14.(i) Whatisthemedicinaluseofnarcotic drugs?(ii)Whyhairwashedwithhardwaterlook dull?(iii)Why glycerol is added to soaps?15.(i) What is the role of benzoyl peroxide in the polymerisation of ethene?(ii)What are LDPE and HDPE? How are they prepared?16.Write the names of monomers of the following polymersandmentiononeimportantuseof each.(i) N(CH ) NC(CH ) C2 6 2 4 nH H O O(ii) (iii) 17.(i) Giveoneimportantuseofeachofthe following :(a)Bithionol(b)Norethindrone(c)Meprobamate(d)Aspartame(ii)What class of drugs is ranitidine?18.(i) Diferentiatebetweenadditionand condensation polymers based on mode of polymerization. Give one example of each type.(ii)Whichpolymerisobtainedwhenfree radicalpolymerisationofchloroprene occurs?Writethestructureofpolymer thus obtained.19.(i) How does the presence of double bonds in rubber molecules infuence their structure and reactivity?(ii)Arrangethepolymersnylon-6,6,buna-S and polythene in increasing order of their intermolecular forces and also give reason for the same.OR(i)Diferentiatebetweennovolacand bakelite on the basis of their structures.(ii)Givetwoexamplesofbiodegradable polymers.(iii)Howdoyouexplainthefunctionalityof monomer?20.(i) Whycimetidineandranitidinearebetter antacidsthanNaHCO3orMg(OH)2or Al(OH)3?(ii)Whyistheuseofaspartamelimitedto cold foods and drinks?21.(i) Whatarebiodegradableandnon-biodegradabledetergents?Whatarethe consequencesofusinglatterclassof detergents?(ii)Labelthehydrophilicandhydrophobic parts in the following compounds :(a)CH3(CH2)10CH2OSO3 Na+(b)CH3(CH2)15N + (CH3)3Br22.(i)Diferentiatebetweennarrowandbroad spectrum antibiotics.(ii)G