Solution of Chapter 18. Model Question Paper-II (Chemistry - Exemplar Book)

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

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

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 dilute HNO₃, it forms a solution of blue colour. Addition of an excess of an aqueous solution of ammonia to this solution will give ________.

What is the IUPAC name of the compound ?

for some half cell reactions are given below. On the basis of these mark the correct answer.

(a)

(b)

(c)

What happens when a lyophilic sol is added to a lyophobic sol?

How do emulsifying agents stabilise emulsion?

On what principle is the zone refining based?

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

Name an artificial sweetener which has dipeptide linkage between two amino acids.

Why does electrical conductivity of semiconductors increase with the rise in temperature?

In the ring test of NO₃^– ion, Fe²⁺ ion reduces nitrate ion to nitric oxide, which combines with Fe²⁺ (aq.) ions to form brown complex. Write reactions involved in the formation of a brown ring.

Arrange the following complex ions in increasing order of crystal field splitting energy Δ0.

[Cr(Cl)₆]^3–, [Cr(CN)6]^3–, [Cr(NH₃)₆]³⁺

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

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

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

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.

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?

How copper is extracted from low-grade copper ores?

A complex of the type [M (AA)₂ X₂]_n⁺ is known to be optically active. What does this indicate about the structure of the complex? Give one example of such complex.

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

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

A primary amine, R—NH₂ can be reacted with alkyl halide, RX, to get secondary amine, R₂NH, but the only disadvantage is that 3° amine and quaternary ammonium salts are also obtained as side products. Can you suggest a method where CH₃NH₂ forms only 2° amine?

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.

A statement of assertion followed by a statement of reason is given. Choose the correct answer out of the option given below each equation.

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.

A statement of assertion followed by a statement of reason is given. Choose the correct answer out of the option given below each equation.

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

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

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.

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 oxidizing 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.

An aromatic compound ‘A’ (Molecular formula C8H8O) 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 C₇H₆O₂) 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’ (C₃H₄) on hyration in presence of H₂SO₄/HgSO₄ gives compound ‘B’ (C₃H₆O). 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’ (C₂H₄O₂) along with formic acid. Identify compounds ‘A’, ‘B’ and ‘C’ and explain all the reactions.