" /> -->

#### Ionic Equilibrium Model Question Paper

12th Standard EM

Reg.No. :
•
•
•
•
•
•

Chemistry

Time : 01:30:00 Hrs
Total Marks : 50
12 x 1 = 12
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. pH of a saturated solution of Ca(OH)2 is 9. The Solubility product ( Ksp) of Ca(OH)2

(a)

0.5 ×10-15

(b)

0.25 ×10-10

(c)

0.125 ×10-15

(d)

0.5 ×10-10

3. Which will make basic buffer?

(a)

50 mL of 0.1M NaOH+25mL of 0.1M CH3 COOH

(b)

100 mL of 0.1M CH3COOH+100 mL of 0.1M NH4OH

(c)

100 mL of 0.1M HCl+200 mL of 0.1M NH4OH

(d)

100 mL of 0.1M HCl+100 mL of 0.1M NaOH

4. Which of these is not likely to act as lewis base?

(a)

BF3

(b)

PF3

(c)

CO

(d)

F

5. The aqueous solutions of sodium formate, anilinium chloride and potassium cyanide are respectively

(a)

acidic, acidic, basic

(b)

basic, acidic, basic

(c)

basic, neutral, basic

(d)

none of these

6. 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%

7. Equal volumes of three acid solutions of pH 1,2 and 3 are mixed in a vessel. What will be the H+ ion concentration in the mixture?

(a)

3.7 ×10-2

(b)

10-6

(c)

0.111

(d)

none of these

8. Using Gibb’s free energy change, ∆Go=57.34 kJ mol-1, for the reaction, X2Y(s)⇌2X++Y2- (aq), calculate the solubility product of X2Y in water at 300 K (R = 8.3 J K-1Mol-1)

(a)

10-10

(b)

10-12

(c)

10-14

(d)

can not be calculated from the given dat

9. What is the pH of the resulting solution when equal volumes of 0.1M NaOH and 0.01M HCl are mixed?

(a)

2.0

(b)

3

(c)

7.0

(d)

12.65

10. The pH of 10-5M KOH solution will be

(a)

9

(b)

5

(c)

19

(d)

none of these

11. The pH of an aqueous solution is Zero. The solution is

(a)

slightly acidic

(b)

strongly acidic

(c)

neutral

(d)

basic

12. Dissociation constant of NH4OH is 1.8 x 10-5  the hydrolysis constant of NH4Cl would be

(a)

1.8 ×10-19

(b)

5.55 ×10-10

(c)

5.55 ×10-5

(d)

1.80 ×10-5

13. 4 x 2 = 8
14. What are lewis acids and bases? Give two example for each.

15. Discuss the Lowery – Bronsted concept of acids and bases.

16. The concentration of hydroxide ion in a water sample is found to be 2.5×10-6M. Identify the nature of the solution.

17. Define solubility product

18. 5 x 3 = 15
19. Define ionic product of water. Give its value at room temperature.

20. Derive an expression for Ostwald’s dilution law

21. Define pH.

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

23. A solution of 0.10M of a weak electrolyte is found to be dissociated to the extent of 1.20% at 25oC . Find the dissociation constant of the acid.

24. 3 x 5 = 15
25. Solubility product of Ag2 CrO4 4 is $1\times10^{-12}$.What is the solubility of Ag2 CrO4 in 0.01M AgNO3 solution?

26. A particular saturated solution of silver chromate Ag2 CrO4 has $[Ag^{+}]=5\times10^{-5}$ and $[CrO_{4}]^{2-}=4.4\times10^{-4}M$.What is the value of Ksp for Ag2 CrO4?

27. 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  $1.8\times10^{-5}$)