Class XI CBSE Chemistry Model Paper

18. Deduce the structural formula of an alkene which on ozonolysls produces propanal and pentanone – 2. 2

19. a) What is Eutrophication ? 1

b) How can photochemical smog be controlled ? 1

c) Give an example of herbicide. 1

20. a) Why atomic radius of Ga is less then the of Al in group 13 ? 1

b) Why white fumes appear around a bottle of anhydrous AlCl3 ? 1

c) Why Sn+2 is a reducing agent but Pb+2 is not ? 1

21. Determine the percentage of Nitrogen in an organic compound, 0.5g of which on kjeldalisation required 10ml of 1M. H2SO4 for complete neuteralisation of the ammonia produced. 3

OR

What is the percentage of sulphur in an organic compound 0.15g of which on subjecting to carius method of suphur estimation produced 0.5g of BaSO4

(Ba = 137, S = 32, O = 16) ? 3

22. a) Explain the structure of diborane by drawing a suitable diagram. 2

b) Why SiCl4 gets hydrolysed but CCl4 does not ? 1

23. a) Write a reaction by which BeCl2 can be prepared. 1 b) Why solvay process can not be extended to manfacture K2CO3 ? 1

c) Why salts of Be can not be detected by flame test ? 1

24. a) Why hard water does not give lather with soap ? 1

b) Complete the reaction and balance it 1

clip_image005 Pbs + H2O2

c) How the presence of Hions be confirmed in Ionic hydrides 1

25. For a reaction , clip_image007H and clip_image007[1]S are 30.56 KJmol-1 and 66JK-1 mol-1 respectively calculate the temperature above which the reaction

would be spontaneous. 3

26. a) Why does the viscosity of a liquid decreases with increase in temp ? 1

B) What is the pressure exerted by 2 mole of a gas enclosed in a 100ml vessel at 270C ? (Given R = 0.0821 lit atm mol-1 K-1) 2

27. a) Why bond angle is NH3 is lower that in CH4 even though the same hybridization is involved in both cases ? 2

b) Why H2O is polar but CO2 is non polar ? 1

28. a) Mention two limitations of Bohr’s Model of atom 2

b) Calculate the wavelength of an electron moving with a kinetic energy of

3×10-25J (mass of electran = 9.8 x 10-31Kg) 3

OR

a) Out at 3d and 4s sub shells which one would have lower

energy and why ? 2

b) What would be the frequency of radiation emitted when an electron moving within a hydrogen atom undergoes transition from fifth to second energy level? 3

29. a) Derive the relationship between kp and kc 3

b) The value of kc for the reaction

2A = B +C is 2 x 10-3. At a given time the composition of reaction mixture is [A] = [B] = [C] = 3 x 10-4 M. In which directions will the reaction proceed? 2