Among the following examples, the species that behave(s) as a Lewis acid is/are: 
\(\mathrm{BF}_3, \mathrm{SnCl}_2, \mathrm{SnCl}_4\)

1. Stannous chloride, Stannic chloride
2. $B{F}_3$, Stannous chloride
3. Only $B{F}_3$
4. $B{F}_3$, Stannous chloride, Stannic chloride

4 gm of NaOH is dissolved in 1000 ml of water. The ${\mathrm{H}}^{+}$ ion concentration will be:

The solubility product of a sparingly soluble salt AX₂ is 3.2 ×10^–11. Its solubility (in moles/litre) is:

1. 3.1×10^–4

2. 2 × 10^–4

3. 4 × 10^–4

4. 5.6 × 10^–6

A compound BA₂ has \(K_{sp} = 4\times 10^{-12}\)$.$ Solubility of this compound will be:

For a reaction , ${\mathrm{BaO}}_2\left(\mathrm{s}\right)\rightleftharpoons \mathrm{BaO}\left(\mathrm{s}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)$; ∆H = + ve. At equilibrium condition, the pressure of O₂ depends on the:

1. Increased mass of BaO₂

2. Increased mass of BaO

3. Increased temperature on equilibrium.

4. Increased mass of BaO₂ and BaO both.

The compound with the highest pH among the following is:

1. CH₃COOK

2. Na₂CO₃

3. NH₄Cl

4. NaNO₃

If a solution of 0.1 N NH₄OH and 0.1 N NH₄Cl has pH 9.25, then pK_b of NH₄OH is:

1. 9.25

2. 4.75

3. 3.75

4. 8.25

A compound, among the following, that cannot be classified as a protonic acid is:

If the solubility product of CuS is 6 × 10^–16, the maximum molarity of CuS in an aqueous solution will be:
1. 1.45 × 10⁻⁸ mol L⁻¹
2. 3.45 × 10⁻⁸ mol L⁻¹
3. 2.45 × 10⁻⁸ mol L⁻¹
4. 4.25 × 10⁻⁸ mol L⁻¹

The volume of the container containing a liquid and its vapours at a constant temperature is suddenly increased. What would be the effect of the change on vapour pressure?
1. It would decrease initially.
2. It would increase initially.
3. It would remain the same.
4. None of the above