Chemistry Question paper

12/18/2011 CBSE

Q1. What is difference between a sol and a gel?

Q2. For the assumed reaction, X2 + 2Y2
è2XY2 write the
rate equation in terms of the rate of disappearance of Y2?

Q3. Name the Xenon fluorides molecule is iso-structural with
IF5 Draw the structure of its molecules?

Q4. What does the prefix η2 in PtCl32-
C2H4) mean?

Q5. Pick odd out of them Equanil, Seconal, Luminal, Bithional?

Q6. Why are carbohydrates optically active?

Q7. Gold crystallizes in FCC arrangement. The edge length is
40.70 nm. Calculate the radius of gold atom?

Q9. What happens when a solution of NaCl is added to Fe(OH)3
sol explain? Write whether Fe(OH)3 sol is a multi-molecular
colloid or macro-molecular colloid?

Q10. Describe the principle of each of the following process

a) Mond’s Process

b) Zone refining

Q11. Complete and balance the following equations:

a) NH3 + NaOCl

b) SCl2 + NaF

Q12. Write monomers, polymers with structures and their uses
for the following polymers:

a) Poly Acrylonitrile (PAN)

b) Poly styrene

Q13. Define the following and give one example of each:

a) F-centre

b) Ionization isomerism in co-ordination compounds

Q14. With the help of suitable diagrams explain negative
deviation from Raoult’s Law also give two examples for the deviation?

Q15. Explain the following giving reasons:

a) Electrolysis of aqueous solution of NaCI gives H2
at cathode and Cl2 gas at anode

b) Electrolysis of aqueous solution of CuBr2
gives Cu at cathode and Br2 at the anode.

Q16. Explain the following observations that tetrahedral Ni
(II) complexes are paramagnetic but square planar Ni (II) complexes are di-magnetic?

Q17. Give two examples of artificial sweeteners. What are
their advantages over natural sweeteners?


Q19. Calculate the normal boiling point of sample of sea water
containing 3.5% NaCl and 0.13% of MgCl2 by mass .Given Kb
= 0.52 K kg mol [wt. of NaCl = 58.5, MgCl2 = 95 g / mol]

Q20. Calculate E°cell, ΔG for the cell  Al|Al
(0.01M) || Fe+2 (0.02M)|
Fe                                                                  Given
Potentials are       Al
è Al+3
+3e- E° = +1.66 V

Fe+2 +2e-
è Fe E° = - 0.44 V

Q21. PbS has NaCI type structure. What is its density if its
edge length is 500 pm? Given [NA = 6.023x 1023, Atomic
weight of Pb= 207.2 and S = 32 a.m.u.]

Q22. If the rate constant of a reaction is 2.0 mol / L / s at
700 K and 32.0 mol/L/ s at 800 K, what is the activation energy?

Q23. Do as directed

a) Give mechanism of conversion of Alcohol to ether

b) Distinguish between the following by suitable chemical

i Phenol and benzoic acid

ii Benzaldehyde and aniline

Q24. Give the following conversions (not more than four

a) An aldehyde to an acetal

b) Phenol to Aspirin

c) Aniline to benzoic acid

Q25. How will you account for the following?

a) Chloro-acetic acid is stronger acid than acetic acid?

b) Ethers possess a net dipole moment even if they are
symmetrical in structure?

c) Aniline is a weaker base than ethyl amine?.

Q26. Explain why it is difficult to prepare pure amines by
ammonolysis of alkyl halide? Give the method that can prepare pure alkyl amines?

Q27. Write short notes on the following:

a) Hell- Volhard Zelinsky Reaction

b) Hofmann’s Bromamide degradation reaction

Q28. Give appropriate reasons for each of the following

a) Sulphur vapour exhibits some paramagnetic behavior 

b) NH3 is more basic the PH3

c) Of the noble gases only xenon is known to form real
chemical compounds.

d) Despite lower electron affinity F2 is stronger
oxidising agent than O2

e) Nitrogen shows little tendency for catenation, whereas
phosphorus shows a clear tendency for catenation.

Q29. Account for the following:

a) Transition elements have higher boiling points

b) Zn, Cd and Hg are normally not regarded as transition

c) Transition metals exhibit higher enthalpies of

d) Transition elements show variable oxidation states

e) Zr resembles with Hafnium.

Q30. Explain giving equations when:

a) Sodium ethoxide is mixed to iso-propyl bromide.

b) Banzaldehyde is mixed with acetaldehyde in dilute
alkaline medium

c) Propane nitrile is treated with tin in dilute
hydrochloric acid

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