Central Board of Secondary Education (CBSE)
Guess Paper – 2011
Class – XI
Subject – Chemistry
1. What is photovoltaic cell?
2. Why HF acid is stored in wax coated glass bottles?
3. What is the molarity of 1 N KMnO4?
4. Give the IUPAC name of
5. Why are Grignard reagents soluble in ether but not in benzene?
6. Give the IUPAC name of
7. Why is bakelite a thermoplastic polymer?
8. What is invert sugar?
9. Equilibrium constant is related to E0cell but not to Ecell, explain why?
Calculate the emf of the cell in which the following reaction takes place:
- Ni (s) + 2Ag+ (0.002 M) ®Ni+2 (0.160 M) +2Ag
Given that E0cell = 1.05 V.
10. Under what condition Van’t hoff factor is,
(i) equal to 1
(ii) greater than 1
(iii) less than 1.
11. What is mercury cell? Give its electrode reaction.
12. What inspired N. Bartlett for carrying out reaction between Xe and PtF6 ?
13. Why the ester hydrolysis is slow in the beginning and becomes faster after some time?
14. Arrange each set of compounds in order of increasing boling points.
Bromoethane, bromoform, chloromethane, dibromomethane.
15. Although electron gain enthalpy of fluorine is less negative as compared to chlorine, fluorine is a stronger oxidizing agent than chlorine. Why?
16. Desribe the features of catalysis by zeolites.
17. Give the chemical test to distinguish between the following pair of compounds:
(i) Ethylamine and Aniline
(ii) Aniline and benzylamine
18. How does the presence of double bonds in rubber molecules influence their
structure and reactivity?
19. Niobium crystallizes in bcc structure. If density is 8.55 g cm-3, calculate atomic
radius of niobium,
given that its atomic mass is 93 u.
20. Two elements A & B form compounds having molecular formula AB2 and AB4.
When dissolved in 20 gm of benzene, 1 gm of AB2 lowers the freezing point
by 2.3 K whereas 1.0 gm of AB4 lowers it by 1.3 K. The molal depression constant for benzene is 5.1 K kg mol-1. Calculate atomic masses of A and B.
21. Describe the principle of froth floatation process. What is the role of stabilizer and of a depressant? Give one example each.
What is the chief ore of iron? Write chemical reactions taking place in the extraction of iron
from its ore by blast furnace.
22. Derive integrated rate equation for rate constant for a first order reaction.
What would be units of the first order rate constant, if the concentration is expressed
in moles per litre and time in seconds?
23. Compete the following reaction:
(i)C6H5CHO + CH3CH2CHO dil.NaOH ?
(iii) ? 2 =O
24. Explain why
(i) The dipole moment of chlorobenzene is lower than that of cyclohexyl
(ii) Sulphuric acid is not used during the reaction of alcohol with KI.
25. What is meant by unidentate, didentate and ambidentate ligands?
Give two examples for each.
26. What happens when D-glucose is treated with the following reagents?
(i) HI (ii) Br2 water (iii) HNO3
27. Explain the following terms with suitable examples.
(i) Anionic detergents (ii) cationic detergents
(iii) neutral detergents.
28. (a) Explain:
(i) In transition metal halides, the highest oxidation state is generally
more stable with
(ii) In transition metal oxides, oxygen stabilizes the highest oxidation
state than flourine. 1
(b) A blackish brown colored solid ‘A’ when fused with alkali metal
hydroxides in presence
of air, produces a dark green colored compound ‘B’, which on
electrolytic oxidation in
alkaline medium gives a dark purple colored compound ‘C’. Identify
A, B and C and
write the reaction involved.
(a) Describe the preparation of K2Cr2O7 from chromite ore. Write the chemical equations
of the reaction involved. What is the effect of pH of a solution of K2Cr2O7?
(b) Represent the reaction of acidified K2Cr2O7 with (i) KI and (ii) FeSO4 with the help of
(c) Draw the structure of chromate ion.
29. (a) How is the presence of SO2 detected?
(b) Why Ka2 is less than Ka1 for H2SO4 in water?
(c) Draw the structure of sulphurus acid.
(a) A translucent white waxy solid (A) on heating in an inert atmosphere is
converted into its allotropic form (B). Allotrope (A) on reaction with very dilute
KOH liberates a highly poisonous gas (C) having rotten fish smell. With excess of
chlorine (C) forms (D) which hydrolyses to compound (E). Identify A toE. Write
all the possible reaction. 5
30. (a) How will you convert the following into benzoic acid?
(i) Benzonitile (ii) toluene.
(b) Write short notes on Etard reaction.
(a) How will you convert ethanal into the following compounds?
(i) Butane-1, 3-diol (ii) But-2-enal
(b) Write short note on Gattermann-Koch reaction.