Solutions Book Back Questions

11th Standard

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Chemistry

Time : 00:45:00 Hrs
Total Marks : 30
5 x 1 = 5
1. The Henry's law constant for the solubility of Nitrogen gas in water at 350 K is 8 × 104 atm. The mole fraction of nitrogen in air is 0.5. The number of moles of Nitrogen from air dissolved in 10 moles of water at 350K and 4 atm pressure is

(a)

4 x 10-4

(b)

4 x 104

(c)

2 x 10-2

(d)

2.5 x 10-4

2. Which one of the following is incorrect for ideal solution?

(a)

$\Delta H_{mix}=0$

(b)

$\Delta U_{mix}=0$

(c)

$\Delta P=P_{observed}-P_{calculated\ by\ raoults\ law}=0$

(d)

$\Delta G_{mix}=0$

3. P1 and P2 are the vapour pressures of pure liquid components, 1 and 2 respectively of an ideal binary solution if x1 represents the mole fraction of component 1, the total pressure of the solution formed by 1 and 2 will be

(a)

P1 + x1 (P2 – P1)

(b)

P2 – x1 (P2 + P1)

(c)

P1 – x2 (P1 – P2)

(d)

P1 + x2 (P1 – P2)

4. Which one of the following binary liquid mixtures exhibits positive deviation from Raoults law?

(a)

Acetone + chloroform

(b)

Water + nitric acid

(c)

HCl + water

(d)

ethanol + water

5. At 100C the vapour pressure of a solution containing 6.5g a solute in 100g water is 732mm. If Kb = 0.52, the boiling point of this solution will be

(a)

102oC

(b)

100oC

(c)

101oC

(d)

100.52oC

6. 3 x 2 = 6
7. How much volume of 6 M solution of NaOH is required to prepare 500 mL of 0.250 M NaOH solution.

8. Explain why the aquatic species are more comfortable in cold water during winter season rather than warm water during the summer.

9. How many moles of solute particles are present in one litre of 10-4 M potassium sulphate?

10. 3 x 3 = 9
11. 0.24 g of a gas dissolves in 1 L of water at 1.5 atm pressure. Calculate the amount of dissolved gas when the pressure is raised to 6.0 atm at constant temperature.

12. The depression in freezing point is 0.24K obtained by dissolving 1g NaCl in 200g water. Calculate van’t-Hoff factor. The molal depression constant is 1.86 K Kg mol-1.

13. 0.2 m aqueous solution of KCl freezes at -0.68ºC calculate van’t Hoff factor. kf for water is 1.86 K kg mol-1.

14. 2 x 5 = 10
15. Calculate the mole fractions of benzene and naphthalene in the vapour phase when an ideal liquid solution is formed by mixing 128 g of naphthalene with 39 g of benzene. It is given that the vapour pressure of pure benzene is 50.71 mmHg and the vapour pressure of pure naphthalene is 32.06 mmHg at 300 K.

16. A sample of 12 M Concentrated hydrochloric acid has a density 1.2 gL–1 Calculate the molality