ZnS is not precipitated by passing H₂S in an acidic medium but CuS is precipitated. The reason for it is

1. ${\mathrm{K}}_{\mathrm{sp}} \mathrm{CuS}<<{\mathrm{K}}_{\mathrm{sp}} \mathrm{ZnS}$

2.${\mathrm{K}}_{\mathrm{sp}} \mathrm{CuS}>>{\mathrm{K}}_{\mathrm{sp}} \mathrm{ZnS}$

3. ${\mathrm{K}}_{\mathrm{sp}} \mathrm{CuS}={\mathrm{K}}_{\mathrm{sp}} \mathrm{ZnS}$

4. None of these

Consider the following acids:

I. HCN

II. CH₃COOH

III. HCOOH

IV. Cl-CH₂COOH

The correct order of strength is

1. II>III>I>IV

2. IV>II>III>I

3. IV>III>II>I

4. III>II>IV>I

The hydrogen ion concentration is 0.2 M ethanoic acid $({\mathrm{K}}_{\mathrm{C}}=2\times {10}^{-5} \mathrm{mol} {\mathrm{dm}}^{-3})$ is approximately

1. ${10}^{-4}$

2. $2\times {10}^{-2}$

3. $2\times {10}^{-6}$

4. $2\times {10}^{-3}$

The pH of a solution made by mixing 50 mL of 0.01 M barium hydroxide solution with 50 mL of H₂O is

Find the molar solubility of Fe(OH)₃ in a buffer solution that 0.10 M in NH₄Cl and 0.10 M in NH₃. If ${\mathrm{K}}_{\mathrm{b}} \left({\mathrm{NH}}_3\right)=1.8\times {10}^{-5}$ and ${\mathrm{K}}_{\mathrm{sp}} \left[\mathrm{Fe}{\left(\mathrm{OH}\right)}_3\right]=2.6\times {10}^{-39}.$

1. $4.458\times {10}^{-25} \mathrm{M}$

2. $3.458\times {10}^{-25} \mathrm{M}$

3. $2.229\times {10}^{-24} \mathrm{M}$

4. $4.458\times {10}^{-22} \mathrm{M}$

A base dissolved in water yields a solution with a hydroxyl ion concentration of 0.05 mol litre^-1. The solution is

1. basic

2. acid

3. neutral

4. either 2 or 3

Ionization constant of CH₃COOH is $1.7\times {10}^{-5}$ and concentration of H⁺ ion is $3.4\times {10}^{-4}$. Then initial concentration of CH₃COOH is

1. $3.4\times {10}^{-4}$

2. $3.4\times {10}^{-3}$

3. $6.8\times {10}^{-4}$

4. $6.8\times {10}^{-3}$

At $25°\mathrm{C}$ the dissociation constant of a base, BOH is $1.0\times {10}^{-12}$, the concentration of hydroxyl ions 0.01 M aqueous solution of the base would become

1. $2.0\times {10}^{-6} \mathrm{mol} {\mathrm{L}}^{-1}$

2. $1.0\times {10}^{-5} \mathrm{mol} {\mathrm{L}}^{-1}$

3. $1.0\times {10}^{-6} \mathrm{mol} {\mathrm{L}}^{-1}$

4. $1.0\times {10}^{-7} \mathrm{mol} {\mathrm{L}}^{-1}$

The solubility product of AgI at $25°\mathrm{C}$ is $1.0\times {10}^{-16} {\mathrm{mol}}^2 {\mathrm{L}}^{-2}$. The solubility of AgI in 10^-4 N solution of KI at $25°\mathrm{C}$ is :  (in mol L^-1)

1. $1.0\times {10}^{-10}$

2. $1.0\times {10}^{-8}$

3. $1.0\times {10}^{-16}$

4. $1.0\times {10}^{-12}$

When 0.1 mole of CH₃NH₂ (ionization constant ${\mathrm{K}}_{\mathrm{b}}=5\times {10}^{-4}$) is mixed with 0.08 mol HCl and the volume is made up of 1 litre. The [H⁺] of resulting solution is -

(log 4 =  0.60)

1. $8\times {10}^{-2}$

2. $2\times {10}^{-11}$

3. $1.23\times {10}^{-4}$

4. $8\times {10}^{-11}$