12th Chemistry C2 Solutions MCQ Test -1

May 25, 2021May 24, 2021 by Mudassar Husain

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12th Chemistry Chapter 2 Solutions MCQ Test -1

1. The molality of pure water is (a) 55.5 (b) 50.5 (c) 18 (d) 60.5

Solutions Class 12 Chemistry MCQs

2. The number of moles of NaCl in 3 litres of 3M solution is (a) 1 (b) 3 (c) 9 (d) 27

Answer: c
Explaination:
(c) 3M solution means 3 moles in 1 litre.
∴ 9 moles in 3 litre.

3. 4L of 0.02 M aqueous solution of NaCl was diluted by adding one litre of water. The molality of the resultant solution is ________ .[NCERT Exemplar] (a) 0.004 (b) 0.008 (c) 0.012 (d) 0.016

Answer: d
Explaination:
(d) M₁V₁ = M₂V₂
0.02 × 4 = M₂ × (4 + 1)
⇒ M₂ = 0.08/5 = 0.016

4. Low concentration of oxygen in the blood and tissues of people living at high altitude is due to _________ .[NCERT Exemplar] (a) low temperature (b) low atmospheric pressure (c) high atmospheric pressure (d) both low temperature and high atmospheric pressure

Answer: b
Explaination:
(b) Low atmospheric pressure will lead to low concentration of oxygen blood.

5. Considering the formation, breaking and strength of hydrogen bond, predict which of the following mixtures will show a positive deviation from Raoult’s law? [NCERT Exemplar] (a) Methanol and acetone. (b) Chloroform and acetone. (c) Nitric acid and water. (d) Phenol and aniline.

Answer: a
Explaination:
(a) CH₃OH and acetone, on mixing force of attraction will decrease.

6. Which of the following aqueous solutions should have the highest boiling point? [NCERT Exemplar] (a) 1.0 M NaOH (b) 1.0 M Na2SO4 (c) 1.0 M NH4NO3 (d) 1.0 M KNO3

Answer: b
Explaination:
(b) Because i = 3, ∆T_b ∝ i, Boiling point ∝ ∆T_b.

7. In comparison to a 0.01 M solution of glucose, the depression in freezing point of a 0.01 M MgCl2 solution is _________ . [NCERT Exemplar] (a) the same (b) about twice (c) about three times (d) about six times

Answer: c
Explaination:
(c) It will be nearly 3 times because number of particles in MgCl₂ → Mg²⁺ + 2Cl^– are thrice than glucose.

8. An unripe mango placed in a concentrated salt solution to prepare pickle, shrivels because _________ . [NCERT Exemplar] (a) it gains water due to osmosis. (b) it loses water due to reverse osmosis. (c) it gains water due to reverse osmosis. (d) it loses water due to osmosis.

Answer: b
Explaination:
(d) Concentrated salt solution is hypertonic solution, therefore, fluids inside mango will come out and it shrivels.

9. Which of the following statements is false? [NCERT Exemplar] (а) Two different solutions of sucrose of same molality prepared in different solvents will have the same depression in freezing point. (b) The osmotic pressure of a solution is given by the equation π = CRT (where C is the molarity of the solution). (c) Decreasing order of osmotic pressure for 0.01 M aqueous solutions of barium chloride, potassium chloride, acetic acid and sucrose is BaCl2 > KCl > CH3COOH > sucrose. (d) According to Raoult’s law, the vapour pressure exerted by a volatile component of a solution is directly proportional to its mole fraction in the solution.

Answer:
Explaination:
(a) is false because ∆T_f will depend upon nature of solvent and their K_f.

10. The value of Henry’s constant KH is _________ .[NCERT Exemplar] (а) greater for gases with higher solubility. (b) greater for gases with lower solubility. (c) constant for all gases. (d) not related to the solubility of gases.

Answer:
Explaination:
(b) Higher the value of K_H, lower will be solubility.

11. We have three aqueous solutions of NaCl labelled as ‘A’, ‘B’ and ‘C’ with concentrations 0.1M, 0.01M and 0.001M, respectively. The value of van’t Hoff factor for these solutions will be in the order __________ . [NCERT Exemplar] (a) iA < iB < iC (b) iA > iB > iC (c) iA = iB = iC (d) iA < iB > iC

Answer: c
Explaination:
(c) van’t Hoff factor (i) does not depend upon concentration.

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