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#### Ionic Equilibrium Model Question Paper 1

12th Standard EM

Reg.No. :
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Chemistry

Time : 01:00:00 Hrs
Total Marks : 50
5 x 1 = 5
1. Concentration of the Ag+ ions in a saturated solution of Ag2C2O4 is 2.24 ×10-4mol L-1 solubility product of Ag2C2O4 is

(a)

2.42 ×10-8mol3L-3

(b)

2.66 ×10-12mol3L-3

(c)

4.5 ×10-11mol3L-3

(d)

5.619 ×10-12mol3L-3

2. Which of the following fluro – compounds is most likely to behave as a Lewis base?

(a)

BF3

(b)

PF3

(c)

CF4

(d)

SiF4

3. The percentage of pyridine (C5H5N) that forms pyridinium ion (C5H5NH) in a 0.10M aqueous pyridine solution (Kb for C5H5N= 1.7×10-9) is

(a)

0.006%

(b)

0.013%

(c)

0.77%

(d)

1.6%

4. MY and NY3, are insoluble salts and have the same Ksp values of 6.2 ×10-13 at room temperature. Which statement would be true with regard to MY and NY3?

(a)

The salts MY and NY3 are more soluble in 0.5M KY than in pure water

(b)

The addition of the salt of KY to the suspension of MY and NY3 will have no effect on their solubility’s

(c)

The molar solubilities of MY and NY3 in water are identical

(d)

The molar solubility of MY in water is less than that of NY3

5. Pick the strongest conjugate base among the following

(a)

Cl-

(b)

${ NO }_{ 2 }^{ - }$

(c)

${ SO }_{ 4 }^{ 2- }$

(d)

CH3COO-

6. 5 x 2 = 10
7. A lab assistant prepared a solution by adding a calculated quantity of HCl gas 250C o to get a solution with [H3O+]= 4$\times$10-5M. Is the solution neutral (or) acidic (or) basic.

8. Define solubility product

9. Calculate the pH of 0.001M HCl solution

10. The KW of a neutral solution is 10-12 at a particular temperature. What are its pH and pOH values?

11. How is common ion effect related to the solubility of the electrolyte?

12. 5 x 3 = 15
13. The Ka value for HCN is 10-9 . What is the pH of 0.4M HCN solution?

14. Calculate the extent of hydrolysis and the pH of 0.1 M ammonium acetate Given that $K_{a}=K_{b}=1.8\times10^{-5}$

15.  Fine the pH of a buffer solution containing 0.20 mole per litre sodium acetate and 0.18 mole per litre acetic acid. Ka for acetic acid is $1.8\times10^{-5}$.

16. What do you mean by auto ionisation of water?

17. For an aqueous solution of NH4CI, prove that [H+ ] = $\sqrt { { K }_{ n }.C }$

18. 4 x 5 = 20
19. What is the pH of an aqueous solution obtained by mixing 6 gram of acetic acid and 8.2 gram of sodium acetate and making the volume equal to 500 ml. (Given: Ka for acetic acid is  $1.8\times10^{-5}$)

20. Calculate i) the hydrolysis constant, ii) degree of hydrolysis and iii) pH of 0.1M CH3COONa solution (pKa for CH3COOH is 4.74).

21. Calculate the pH of 0.1 M acetic acid if its ionisation constant Ka = 1.8 X 10-5.

22. pH of a solution is 5.5 at 25°C. Calculate its [OH-].