CBSE Board Guess Paper – 2011
Class – 12th
Subject –Chemistry
Time: 3 Hrs Max Marks: 70
General Instructions:
i. All questions are compulsory.
ii. Questions 1 to 8 are very short answer type carrying 1 mark each. Answer them in one sentence each.
iii. Questions 9 to 18 are short answer type carrying 2 marks each. Answer each of them in about 30 words.
iv. Questions 19 to 27 are also short answer type carrying 3 marks each. Answer each of them in about 40 words.
v. Questions 28, 29 & 30 are long answer type carrying 5 marks each. Answer each of them in about 70 words.
vi. Calculators are not permitted. Use log tables if necessary.
Section-A
1. Define the elementary reaction . 1
2. Write IUPAC name of: C6H5 NHCOCH3 1
3. Write example of water in oil type colloid. 1
4. What is rate constant and how does its values vary with reactant concentration. 1
5. In the ring test for identification of nitrate ion ,what is formula of the compound responsible for brown ring formed at the interface of 2 liquids? 1
6. A reaction is 50% complete in 2 hours and 75% in 4 hours what is order of the reaction?. 1
7. Why transition metals act as good catalyst? 1
8. Define the term Ionization isomerism in co-ordination compounds. 1
Section-B
9. (i) How many faraday of charge is required for conversion of C6H5NO2 into C6H5NH2?
(ii) During electrolysis of NaOH, Cl2 and H2 while for molten NaCl only Na metal and Cl2 gas are obtained. Explain these observations with suitable equation. 2
10. Discuss nature of bonding and magnetic property of the complex [Fe (CN)6 ]3- according to V.B theory. At. Number of Fe = 26. 2
OR
(i) What is spectrochemical series?
(ii) Why are certain monodentate ligands called ‘ambidentate’? Give example.
11. Give Reasons: 2
(a) Amines are weaker acids than alcohols.
(b) Phenol does not undergo acid catalyzed dehydration.
12. (a) Can the substance act both as colloid and crstalloid. 1
(b) Why hydrophillic sols are more than hydrophobic sols. 1
13. Unlike phenols, alcohols are easily protonated. 2
14. How will you distinguish between
a. Ethylamine and aniline. 1
b. Methyl amine and dimethylamine. 1
15. Discuss the contact process of preparation of sulphuric acid . 2
16. What are the properties of a d-block elements which make them a good catalyst? 2
17. (a) N2 is least reactive at room temperature .explain.
(b) Write the isoelectronic neutral species of ClO-1 .
18. How do you distinguish? 2
(i) Phenol & p-Cresol
(ii) Propanol and ethanol
Section – C
19. Explain the following term . 3
i. Ferromagnetism
ii. Tetrahedral void
iii. Frankel defect .
20. The time required for 10% completion of a first order reaction at 298 K is equal to that required for its 25% completion at 308 K.If the value of A is 4x1010 /s .Calculate k at 318 K and Ea. 3
21. (a) Draw the structure of SF4,BrF3. 1x 3
(b) P4 + HNO3 (conc) ---- → ?
(c) How is the sulphuric acid prepared ?
22. (a) What are biodegradable polymer. Give an equation of biodegradable aliphatic polyester. (1+1)
(b) Define chemotherapy. 1
23. Clasify detergents giving an eample in each case. 3
24. (a) The hexaaquamaganese (ii) ion contains five unpaired electrons,while the hexacyanomanganese(ii) ions only contain one unpaired electron.explain using crystal fielf theory. 2
(b) What is basis of formation of the spectrochemical series. 1
25. (i) Why calculations based on colligate properties of solutions sometimes gives abnormal molecular mass values for solute? What is the nature of the abnormalities?
(ii) 2g of C6 H5 COOH dissolved in 25g of benzene shows a depression in freezing point equal to 1.62 K. Molal depression constant for benzene is 4.9K kg mol-1. What is the Percentage (%) of association of acid, if it forms a dimer in solution? 3
26. Account for the following: 3
(i) Chlorobenzene is less reactive towards Nucleophilic substitution.
(ii) Ethyl amine has lower boiling point than ethyl alcohol.
(iii) pKa of ethanoic acid is greater than that of chloroethanoic acid.
27. (a) What are chain growth and step growth polymerization? Give examples. 3
(b) Write preparation of: (i) Novolac (ii) Teflon
Section – D
28. (a) Complete the following chemical equations and balance them.
(i) NH3(excess) + Cl2 →
(ii) P4 + NaOH + H2O →
(iii) XeF4 + SbF5 →
(b) Describe the contact process for the manufacture of sulphuric acid. Write the conditions required to maximize the yield of sulphuric acid. Write equations to illustrate following properties of sulphuric acid:
(i) Strong acidic character
(ii) Low volatility
(iii) Dehydrating nature
(iv) Oxidizing action. 5
29. (i) A reaction is 1st order in A and second order in B
(a) Write differential rate equation.
(b) How is the rate affected when concentration of B is tripled?
(c) How is the rate affected when concentration of both A & B is doubled?
(ii) The kinetics of the reaction: A + 2B → Products; obeys the rate equation Rate = k [A]1[B]1 for it, find:
a) Order of the reaction
b) Apparent molecularity of reaction
c) Order of reaction when B is in large excess. 5
30. (a) An organic compound with molecular formula c9h10o( c-9 ,h-10,o) forms2,4-dnp derivative ,reduces tollens reagent and undergoes cannizzaro reaction. On vigorous oxidation it gives 1,2-benzenedicarboxylic acid.identify the compound. 3
(b) how will you convert
i.Benzoic acid to m-nitrobenzoic acid 1
ii. Ethanol to acetone. 1