Class XII Chemistry (Code 043) Sample Question Paper Time allowed: 3 Hours Max. Marks: 70

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1 Class XII Chemistry (Cde 04) Sample Questin Paper Time allwed: Hurs Max. Marks: 70 General Instructins: (a) All questins are cmpulsry. (b) Sectin A: Q.n. 1 t are very shrt answer questins and carry 1 mark each. (c) Sectin B: Q.n. 6 t 1 are shrt answer questins and carry marks each. (d) Sectin C: Q.n. 1 t 4 are als shrt answer questins and carry marks each. (e) Sectin D: Q.n. t 7 are lng answer questins and carry marks each. (f) There is n verall chice. Hwever an internal chice has been prvided in tw questins f ne mark, tw questins f tw marks, fur questins f three marks and all the three questins f five marks weightage. Yu have t attempt nly ne f the chices in such questins. (g) Use f lg tables if necessary, use f calculatrs is nt allwed. Sectin-A 1. ZnO crystal n heating acquires the frmula Zn 1+x O. Give reasn. 1 There is an increase in cnductivity when Silicn is dped with Phsphrus. Give reasn. Based n the type f dispersed phase, what type f cllids are micelles? 1. On the basis f crystal field thery, write the electrnic cnfiguratin f d 6 in terms f t 1 g and e g in an ctahedral field when P. Lw spin cnfiguratin are rarely bserved in tetrahedral crdinatin entity frmatin. Explain 4. Identify the cmpund that n hydrgenatin prduces an ptically active cmpund frm the fllwing cmpunds: 1 H C H Br CH Br H (A) CH H C (B). Write the name f the bidegradable plymer used in rthpaedic devices. 1 1

2 Sectin-B 6. Calculate the freezing pint f a slutin cntaining 8.1 g f HBr in 100 g f water, assuming the acid t be 90 % inized. [Given: Mlar mass Br = 80 g/ml, K f water = 1.86 K kg / ml] Calculate the mlality f ethanl slutin in which the mle fractin f water is Identify the reactin and write the IUPAC name f the prduct frmed: (a) CH -CH -COOH (i) Br / Red phsphrus (b) O Cl H Pd - BaSO 4 Write the structures and IUPAC names f the crss aldl cndensatin prducts nly f ethanal and prpanal. 8. (a) Justify the rle f tert-butyl perxide in the plymerizatin f ethene. (b) Write the structures f the mnmers f the fllwing plymer: C 6 H CH - CH = CH - CH - CH -CH 9. Write the mechanism f acid dehydratin f ethanl t yield ethane 10. Fr a certain chemical reactin variatin in cncentratin [A] vs. time (s) plt is given belw: n (i) Predict the rder f the given reactin? (ii) What des the slpe f the line and intercept indicate? (iii) What is the unit f rate cnstant k?

3 11. Draw the mlecular structures f the fllwing: (a) Nble gas species which is isstructural with (b) Dibasic xacid f phsphrus BrO 1. (i) On the basis f the standard electrde ptential values stated fr acid slutins, predict whether Ti 4+ species may be used t xidise Fe(II) t Fe(III) 4 Ti e Ti E 0.01V Fe e Fe E 0.77V (ii) Based n the data arrange Fe +, Mn + and Cr + in the increasing rder f stability f + xidatin state.(give a brief reasn) E Cr / Cr 0.4V E E Mn / Mn Fe / Fe 1.V 0.8V Sectin-C 1. Nibium crystallises in bdy-centred cubic structure. If the atmic radius is 14.1 pm, calculate the density f Nibium. (Atmic mass = 9u). 14. Give reasns fr the fllwing: a. When g f benzic acid is disslved in g f benzene, the experimentally determined mlar mass is always greater than the true value. b. Mixture f ethanl and acetne shws psitive deviatin frm Rault s Law. c. The preservatin f fruits by adding cncentrated sugar slutin prtects against bacterial actin. 1. An alchl A (C 4 H 10 O) n xidatin with acidified ptassium dichrmate gives acid B (C 4 H 8 O ). Cmpund A when dehydrated with cnc. H SO 4 at 44 K gives cmpund C. Treatment f C with aqueus H SO 4 gives cmpund D (C 4 H 10 O) which is an ismer f A. Cmpund D is resistant t xidatin but cmpund A can be easily xidised. Identify A, B, C and D. Name the type f ismerism exhibited by A and D 16. Which ne f the fllwing cmpunds will underg faster hydrlysis reactin by S N 1 mechanism? Justify yur answer. CH Cl r CH CH CH Cl A cmpund is frmed by the substitutin f tw chlrine atms fr tw hydrgen atms in prpane. Write the structures f the ismers pssible. Give the IUPAC name f the ismer which can exhibit enantimerism.

4 17. Cmplete the fllwing reactins : (a) (b) O + H N OH KMnO 4, H SO 4 (c) COOH COOH + NH Strng heating 18. Give reasns fr the fllwing: (i) Use f aspartame as an artificial sweetener is limited t cld fds. (ii) Metal hydrxides are better alternatives than sdium hydrgen carbnate fr treatment f acidity. (iii) Aspirin is used in preventin f heart attacks. 19. (a) Name the branched chain cmpnent f starch. (b) Ribse in RNA and dexyribse in DNA differ in the structure arund which carbn atm? (c) Hw many peptide linkages are present in a tripeptide? Give three reactins f glucse which cannt be explained by its chain structure 0. The fllwing data were btained during the first rder thermal decmpsitin f N O (g) at a cnstant vlume: NO ( g) NO4 ( g) O ( g) S.N. Time (sec.) Ttal pressure(atm) Calculate the rate cnstant Tw reactins f the same rder have equal pre expnential factrs but their activatin energies differ by 4.9 kj ml -1. Calculate the rati between the rate cnstants f these reactins at 7 C. (Gas cnstant R = 8.14 J K 1 ml 1 ) 4

5 1. (a) A cllidal sl is prepared by the given methd in figure. What is the charge f AgI cllidal particles in the test tube? Hw is the sl frmed, represented? (b) Explain hw the phenmenn f adsrptin finds applicatin in Hetergeneus catalysis. (c) Which f the fllwing electrlytes is the mst effective fr the cagulatin f Fe(OH) sl which is a psitively charged sl? NaCl, Na SO 4, Na PO 4. Describe hw the fllwing steps can be carried ut? (a) Recvery f Gld frm leached gld metal cmplex.. (b) Cnversin f Zircnium idide t pure Zircnium. (c) Frmatin f slag in the extractin f cpper. (Write the chemical equatins als fr the reactins invlved) Explain the use f the fllwing: a) NaCN in Frth Flatatin Methd. b) Carbn mnxide in Mnd prcess. c) Cke in the extractin f Zinc frm Zinc Oxide. Explain the fllwing: (a) Out f Sc +, C + and Cr + ins, nly Sc + is clurless in aqueus slutins. (Atmic n.: C = 7; Sc = 1 and Cr = 4) (b) The E Cu / Cu fr cpper metal is psitive (+0.4), unlike the remaining members f the first transitin series (c) La(OH) is mre basic than Lu(OH). 4. A metal cmplex having cmpsitin Cr (NH ) 4 Cl Br has been islated in tw frms A and B. The frm A reacts with AgNO t give a white precipitate readily sluble in dilute aqueus ammnia whereas B gives a pale yellw precipitate sluble in cncentrated ammnia. (i) Write the frmulae f ismers A and B. (ii) State the hybridisatin f chrmium in each f them. (iii) Calculate the magnetic mment (spin nly value) f the ismer A

6 Sectin-D. (a) Identify A-D CH Cl CH NO A Sn / HCl B NaOH(aq)/Br C D CH NC (b) (c) Distinguish between the fllwing pair f cmpunds: (i) Aniline and Benzylamine. (ii) Methylamine and Dimethylamine. Cmplete the fllwing: CH CH CN 0 LiAlH 4 0 C / HNO A B (a) Accunt fr the fllwing: (i) (ii) Direct nitratin f aniline yields significant amunt f meta derivative. Primary armatic amines cannt be prepared by Gabriel phthalimide synthesis. (b) Carry ut the fllwing cnversins: (i) Ethanic acid int methanamine. (ii) Aniline t p-brmaniline. (c) Arrange the fllwing in increasing rder f basic strength: Aniline, p-nitraniline and p-tludine. 6. (a) A cell is prepared by dipping a zinc rd in 1M zinc sulphate slutin and a silver electrde in 1M silver nitrate slutin. The standard electrde ptential given: E 0 Zn+ / Zn = V, E 0 Ag+ / Ag = V What is the effect f increase in cncentratin f Zn + n the E cell? (b) Write the prducts f electrlysis f aqueus slutin f NaCl with platinum electrdes. (c) Calculate e.m.f. f the fllwing cell at 98 K: Ni(s) / Ni + (0.01 M) // Cu + (0.1M) / Cu (s) [ Given E 0 Ni+/ Ni = - 0. V, E 0 Cu+/Cu = V ) Write the verall cell reactin. 6

7 (a) Apply Khlrausch law f independent migratin f ins, write the expressin t determine the limiting mlar cnductivity f calcium chlride. (b) Given are the cnductivity and mlar cnductivity f NaCl slutins at 98K at different cncentratins: Cncentratin M Cnductivity Scm -1 Mlar cnductivity S cm ml x x x Cmpare the variatin f cnductivity and mlar cnductivity f NaCl slutins n dilutin. Give reasn. (c) 0.1 M KCl slutin ffered a resistance f 100 hms in a cnductivity cell at 98 K. If the cell cnstant f the cell is 1.9 cm -1, calculate the mlar cnductivity f KCl slutin. 7. (a) Accunt fr the fllwing bservatins: (b) What happens when (i) SF 4 is easily hydrlysed whereas SF 6 is nt easily hydrlysed (ii) Chlrine water is a pwerful bleaching agent. (iii) Bi(V) is a strnger xidising agent than Sb(V) (i) White phsphrus is heated with cncentrated NaOH slutin in an inert atmsphere f CO. (ii) XeF 6 underges partial hydrlysis. (Give the chemical equatins invlved). (a) What inspired N.Bartlett fr carrying ut reactin between Xe and PtF 6? (b) Arrange the fllwing in the rder f prperty indicated against each set: (i) F, I, Br, Cl (increasing bnd dissciatin enthalpy) (ii) NH, AsH, SbH, BiH, PH (decreasing base strength) (c) Cmplete the fllwing equatins: (i) Cl NaOH ( cld and dilute ) (ii) Fe SO HO 7