Sample Paper II

Question 1. Which of the following statements is not true for hexagonal close packing?

(i) The coordination number is 12

(ii) It has 74% packing efficiency

(iii) Octahedral voids of second layer are covered by spheres of the third layer.

(iv) In this arrangement third layer is identical with the first layer.

Question 2. Brine is electrolysed using inert electrodes. The reaction at anode is _____.

(i) $Cl^– (aq.) \rightarrow \frac{1}{2} Cl_2 (g) + e^– ; E_{Cell}^{\ominus} = 1.36V$

(ii) $2H_2O (l) \rightarrow O_2 (g) + 4H^+ + 4e^– ; E_{Cell}^{\ominus} = 1.23V$

(iii) $Na^+ (aq.) + e^– \rightarrow Na(s) ; E_{Cell}^{\ominus} = 2.71V$

(iv) $H^+ (aq.) + e^– \rightarrow \frac{1}{2} H_2 (g) ; E_{Cell}^{\ominus} = 0.00V$

Question 3. In a qualitative analysis when H2S is passed through the solution of a salt acidified with HCl, a black precipitate is obtained. On boiling the precipitate with dil. $HNO_3$, it forms a solution of blue colour. Addition of excess of aqueous solution of ammonia to this solution will give ________.

(i) Deep blue precipitate of $Cu(OH)_2$.

(ii) Deep blue solution of $[Cu (NH_3)_4]^{2+}$.

(iii) Deep blue solution of $Cu(NO_3)_2$.

(iv) Deep blue solution of $Cu(OH)_2.Cu(NO_3)_2$.

Question 4. What is the IUPAC name of the compound ?

(i) N, N-Dimethylaminobutane

(ii) N, N-Dimethylbutan-1-amine

(iii) N, N-Dimethylbutylamine

(iv) N-methylpentan-2-amine

Question 5. $E_{Cell}^{\ominus}$ for some half cell reactions are given below. On the basis of these mark the correct answer.

(a) $H^+ (aq.) + e^– \rightarrow \frac{1}{2} H_2 (g) ; E_{Cell}^{\ominus} = 0.00V$

(b) $2H_2O (l) \rightarrow O_2 (g) + 4H^+ (aq.) + 4e^– ; E_{Cell}^{\ominus} = 1.23V$

(c) $2SO_4^{2–} (aq.) \rightarrow S_2O_8^{2–} (aq.) + 2e^– ; E_{Cell}^{\ominus} = 1.96 V$

(i) In dilute sulphuric acid solution, hydrogen will be reduced at cathode.

(ii) In concentrated sulphuric acid solution, water will be oxidised at anode.

(iii) In dilute sulphuric acid solution, $SO_4^{2–}$ ion will be oxidised to tetrathionate ion at anode.

(iv) In dilute sulphuric acid solution, water will be oxidised at anode.

Question 6. What happens when a lyophilic sol is added to a lyophobic sol?

(i) Lyophobic sol is protected.

(ii) Lyophilic sol is protected.

(iii) Film of lyophilic sol is formed over lyophobic sol.

(iv) Film of lyophobic sol is formed over lyophilic sol.

Question 7. How do emulsifying agents stabilise emulsion?

Question 8. On what principle is the zone refining based?

Question 9. Why cross links are required in rubber to have practical applications?

Question 10. Name an artificial sweetener which has dipeptide linkage between two aminoacids.

Question 11. Explain why does conductivity of germanium crystals increases on doping with gallium.

Question 12. In the ring test of $NO_3^–$ ion, $Fe^{2+}$ ion reduces nitrate ion to nitric oxide, which combines with $Fe^{2+}$ (aq.) ions to form brown complex. Write reactions involved in the formation of brown ring.

Question 13. Arrange the following complex ions in increasing order of crystal field splitting energy $\Delta_0$.

$[Cr(Cl)_6]^{3–}, [Cr(CN)_6]^{3–}, [Cr(NH_3)_6]^{3+}$

Question 14. Explain why allyl chloride is hydrolysed more readily than n-propylchloride?

Question 15. Write name(s) of starting materials for the following polymer and idntify its monomer unit.

Question 16. What is the advantage of using antihistamines instead of antacids in the treatment of hyperacidity.

Question 17. When 1 mol of NaCl is added to 1 litre of water, the boiling point of water increases. On the other hand, addition of 1 mol of methyl alcohol to one litre of water decreases the boiling point of water. Explain why does this happen.

Question 18. Value of standard electrode potential for the oxidation of $Cl^–$ ion is more positive than that of water, even then in the electrolysis of aqueous sodium chloride solution, why is $Cl^–$ oxidised at anode instead of water?

Question 19. How copper is extracted from low grade copper ores?

Question 20. Calculate the volume of 0.1 M NaOH solution required to neutralise the products formed by dissolving 1.1 g of $P_4O_6$ in $H_2O$.

Question 21. A complex of the type $[M (AA)_2 X_2]^{n+}$ is known to be optically active. What does this indicate about the structure of the complex? Give one example of such complex.

Question 22. Predict the major product formed on adding HCl to isobutylene and write the IUPAC name of the product. Explain the mechanism of the reaction.

Question 23. Explain why rate of reaction of Lucas reagent with three classes of alcohols different? Give chemical equations wherever required.

Question 24. A primary amine, $R—NH_2$ can be reacted with alkyl halide, RX, to get secondary amine, $R_2NH$, but the only disadvantage is that 3° amine and quaternary ammonium salts are also obtained as side products. Can you suggest a method where $CH_3NH_2$ forms only 2° amine?

Question 25. Label the glucose and fructose units in the following disaccharide and identify anomeric carbon atoms in these units. Is the sugar reducing in nature? Explain.

Question 26. Assertion : When NaCl is added to water a depression in freezing point is observed.

Reason : The lowering of vapour pressure of a solution causes depression in the freezing point.

(i) Assertion and reason both are correct statements and reason is correct explanation for assertion.

(ii) Assertion and reason both are correct statements but reason is not correct explanation for assertion.

(iii) Assertion is correct statement but reason is wrong statement.

(iv) Assertion and reason both are incorrect statements.

(v) Assertion is wrong statement but reason is correct statement.

Question 27. Assertion : Bond angle in ethers is slightly less than the tetrahedral angle.

Reason : There is repulsion between the two bulky (—R) groups.

(i) Assertion and reason both are correct statements and reason is correct explanation for assertion.

(ii) Assertion and reason both are correct statements but reason is not correct explanation for assertion.

(iii) Assertion is correct statement but reason is wrong statement.

(iv) Assertion and reason both are incorrect statements.

(v) Assertion is wrong statement but reason is correct statement.

Question 28. Explain why does the enthalpy change of a reaction remain unchanged even when a catalyst is used in the reaction.

or

With the help of an example explain what is meant by pseudo first order reaction.

Question 29. When a chromite ore (A) is fused with sodium carbonate in free excess of air and the product is dissolved in water, a yellow solution of compound (B) is obtained. After treatment of this yellow solution with sulphuric acid, compound (C) can be crystallised from the solution. When compound (C) is treated with KCl solution, orange crystals of compound (D) crystallise out. Identify compounds A to D and also explain the reactions.

or

An oxide of mangnese (A) is fused with KOH in the presence of an oxidising agent and dissolved in water. A dark green solution of compound (B) is obtained. Compound (B) disproportionates in neutral or acidic solution to give purple compound (C). Alkaline solution of (C) oxidises potassium iodide solution to a compound (D) and compound (A) is also formed. Identify compounds A to D and also explain the reactions involved.

Question 30. An aromatic compound ‘A’ (Molecular formula $C_8H_8O$) gives positive 2, 4-DNP test. The compound gives a yellow precipitate of compound ‘B’ on treatment with iodine and sodium hydroxide solution. It does not give Tollen’s or Fehling’s test. On drastic oxidation with potassium permanganate it forms a carboxylic acid ‘C’ (Molecular formula $C_7H_6O_2$) which is also formed along with the yellow compound in the above reaction. Identify compounds A, B and C and write all the reactions involved.

or

An organic compud ‘A’ ($C_3H_4$) on hyration in presence of $H_2SO_4/HgSO_4$ gives compound ‘B’ ($C_3H_6O$). Compound ‘B’ gives white crystalline product (D) with sodium hydrogensulphite. It gives negative Tollen’s test and positive iodoform’s test. On drastic oxidation ‘B’ gives compound ‘C’ ($C_2H_4O_2$) along with formic acid. Identify compounds ‘A’, ‘B’ and ‘C’ and explain all the reactions.