CBSE Sample Paper for Class 11 Chemistry (Solved) – Set D
There is no overall choice in the paper. However, there is n internal choice in one question of 2 marks weight-age, one question of 3 marks weight-age and all t three questions of 5 marks weight age. Please note that the paper given here is only a sample. You can use log table if necessary. Use of calculator is not permitted. Set E of Solved CBSE Sample Paper for Class 11 Chemistry is given below with its solutions.
Sample Question Paper
1. How many quantum numbers are required to specify an orbital ? 
2. What is the shape of SF6 ? [HOTS] 
3. What is compressibility factor ? 
4. What is the oxidation number of S in the reactants and the products : [HOTS] 
2Na2S2O3 + 12 —> Na2S4O6 + 2Nal
5. What do you mean by 15 volume H2O2 solution ? 
6. A hydrocarbon has 92.3% carbon and 7.7% hydrogen. The molecular mass of the compound is 26. Calculate the empirical formula of the hydrocarbon. 
7. If the density of methanol is 0.793 kg L-1, what is its volume needed for making 2.5 L of its 0.25 M solution ? 
8. Which of the following reactions will get affected by increasing the pressure ? Also mention whether change will cause the reaction to go into forward or backward direction ? 
(a) COC12(g) ⇔CO(g) + C12(g)
(b) CH4(g) + 2S2(g) ⇔ CS2(g) + 2H2S(g)
9. How is green chemistry useful for dry cleaning of clothes ? 
10. Explain why the following systems are not aromatic ?
Write bond line structural formula for : 
(b) 2, 2, 4-Trimethylpentane
11. Write the complete symbol for the atom with the given atomic number (Z) and atomic mass (A). 
(i) Z = 17, A = 35,
(ii) Z = 92, A = 233,
(iii) Z = 4, A = 9
12. The ejection of the photoelectron from the silver metal in the photoelectric effect experiment can be stopped by applying a voltage of 0.35 V when the radiation 256.7 nm is used. Calculate the work function for silver metal. 
13. Although both CO3 and H2O are triatomic molecules, the shape of H2O molecule is bent while that of CO2 is linear. Explain these on the basis of dipole moment. 
14. Try all possible approaches to justify that the following reactions are redox reactions. 
(a) CuO(s) + H2(g) → CU(S) + H30(g)
(b) Fe2O3(s) + 3C0(g) → 2Fe(s) + 3CO2(g)
(c) 4BC13(s) + 3LiA1H4(s) → 2B2H6(g) + 3LiC1(s) + 3A1C13(s)
15. Why is anhydrous barium peroxide not used in the preparation of H2O2 ? How does hydrogen peroxide react with : 
(ii) Moist silver oxide.
16. BeF2 molecule is linear while SF2 is angular though both are triatomic. Explain. 
17. Equilibrium constant K, for the reaction : [HOTS] 
N2(g) + 3H2(g) —> 2NH3(g) at 500K is 0.061.
At particular time analysis shows that composition of the reaction mixture is 3.0 mo/L N2 2.0 mol/L NH3. Is the reaction at equilibrium ? If not in which direction does the
reaction tend to proceed to equilibrium and why ?
18. (i) Density of gas is found to be 5.461dm3 at 27°C at 2 bar pressure. What will be its density at STP ?
(ii) Critical temperature for CO2 and CH4 are 31.1°C and – 81.9°C respectively. Which of these has stronger intermolecular forces and why ? [2 + 1]
19. What would have happened if the green house gases were totally missing in the earth’s atmosphere ?
20. How would you convert benzene into : 
(iii) Ethyl benzene.
21. Differentiate between the principle of estimation of nitrogen by Duma’s method and Kjeldahl’s method. 
22. Describe one important use of each of the following : 
(i) caustic soda,
(ii) sodium carbonate,
(iii) quick lime.
Explain significance of sodium, potassium and calcium in biological fluids. 
23. When an electron is added to a neutral gaseous atom to convert it into a negative ion, the enthalpy change accompanying the process is defined electron gain enthalpy. Electron gain enthalpy provides a measure of the ease with which an atom adds an electron to form anion. Depending on the element, the process of adding an electron to the atom can be either endothermic or exothermic. For many elements energy is released when an electron is added to the atom and the electron gain enthalpy is negative.
Now answer the following questions :
(i) Which of the following pairs of elements would you have a more negative electron gain enthalpy. (i) 0 or F F or Cl. [Value Based Question] 
(ii) Would you expect the second electron gain enthalpy of 0 as positive, more negative or less negative than the first ? Justify your answer. [Value Based Question] 
24. (i) Given : N2(g) + 3H2(g) → 2NH3(g) ; Δr H° = – 92.4 kJ mo1-1. What is the standard enthalpy of formation of NH3 gas ?
(ii) Calculate the standard enthalpy of formation of CH3OH(1) from the following data :
(a) CH3OH(l) + 3/2O2(g) → CO2(g) + 2H2O(l) ; ΔrH° = – 726 kJ mol-1
(b) C(s) + O2(g) → CO2(g) ; ΔcH° = – 393 10 mo1-1
(c) H2(g) + 1/2 O2(g) → H2O(/) ; ΔfH° = – 286 kJ mo1-1. [HOTS] 
For an isolated system, ΔU = 0, what will be ΔS?
Calculate the enthalpy change for the process
CC14(g) → C(g) + 4C1(g)
and calculate bond enthalpy of C—Cl in CC14(g)
Given :Δvap H° (CC14) = 30.5 kJ mo1-1, ΔfH° (CC14) = – 135.5 kJ mol-1
Δa H° (C) = 715.0 kJ mo1-1 where Δa H° is enthalpy of atomisation.
Δa H° (C12) = 242 kJ mo1-1. [HOTS] 
25. A welding fuel gas contains C and H only. Burning a small sample of it in oxygen gives 3.38 gm CO2, 0.690 gm H2O and no other product. A volume of 10 L at S.T.P. of this gas is
found to weigh 11.6 gm. Calculate :
(i) Empirical formula,
(ii) Molar mass of gas,
(iii) Molecular formula. 
(a) What is chromatography and Rf value ? 
(b) A sample of 0.50 gm of organic compound was treated according to Kjeldahl method. The ammonia evolved was absorbed in 50 ml of 0.5 M. The residual acid required 60 ml of 0.5 M solution of NaOH for neutralisation. Find the percentage composition of nitrogen in the compound. 
26. (a) Explain what happens when boric acid is heated. 
(b) How can you explain higher stability of BC13 as compared to T1C13 ? .
(c) Why does boron trifluoride behave as a Lewis acid ? 
(a) If B—Cl bond has a dipole moment, explain why BCI3 molecule has zero dipole moment. 
(b) Aluminium trifluride is insoluble in anhydrous HF but dissolves on addition of NaF. Alluminium trifluoride precipitates out of the resulting solution when gaseous BF3 is
bubbled through. Give reasons.