1

### AIPMT 2004

The solubility product of a sparingly soluble salt AX2 is 3.2 $\times$ 10$-$11. Its solubility (in moles/L) is
A
5.6 $\times$ 10$-$6
B
3.1 $\times$ 10$-$4
C
2 $\times$ 10$-$4
D
4 $\times$ 10$-$4

## Explanation

AX2 A2+ + 2X-
s s 2s

Ksp = = [A2+] [X ]2 = s × (2s)2 = 4s3

$\Rightarrow$ 3.2 $\times$ 10$-$11 = 4s3

$\Rightarrow$ s3 = 8 × 10–12

$\Rightarrow$ s = 2 × 10–4 mol L–1
2

### AIPMT 2003

The solubility product of AgI at 25oC is 1.0 $\times$ 10$-$16 mol2 L$-$2. The solubility of AgI in 10$-$4 N solution of KI at 25oC is approximately (in mol L$-$1
A
1.0 $\times$ 10$-$16
B
1.0 $\times$ 10$-$12
C
1.0 $\times$ 10$-$10
D
1.0 $\times$ 10$-$8

## Explanation

AgI Ag+ + I-
s s s

Ksp = s2

$\Rightarrow$ 1.0 × 10–16 = s2

$\Rightarrow$ s = 1.0 × 10–8 mol L–1

$\therefore$ [Ag+] = 1.0 × 10–8 mol L–1

Also, in 10–4 N KI solution,

[I–1] = (10–4 + 1.0 × 10–8) mol L–1

$\Rightarrow$ [I–1] = (10–4) mol L–1

[As 1.0 × 10–8 mol L–1 << 1.0 × 10–4 mol L–1]

$\therefore$ Ksp of AgI = [Ag+][I]

= (1.0 × 10–8)(10–4)

= 1.0 × 10–12 mol L–1
3

### AIPMT 2003

The reaction quotient (Q) for the reaction

N2(g) + 3H2(g) $\rightleftharpoons$ 2NH3(g) is given by

$Q = {{{{\left[ {N{H_3}} \right]}^2}} \over {\left[ {{N_2}} \right]{{\left[ {{H_2}} \right]}^3}}}$.

The reaction will proceed from right to left if
A
Q = Kc
B
Q < Kc
C
Q > Kc
D
Q = 0

## Explanation

For any reaction to process in forward direction the reaction quotient (Q) must be less than equilibrium constant KC.

Q < Kc
4

### AIPMT 2003

Which one of the following statements is not true?
A
Among halide ions, iodide is the most powerful reducing agent.
B
Fluorine is the only halogen that does not show a variable oxidation state.
C
HOCl is a stronger acid than HOBr.
D
HF is a stronger acid than HCl.

## Explanation

F is more electronegative than Cl therefore HF bond is stronger than HCl and hence proton is not given off easily and hence HF is a weakest acid.