The conjugate bases of Bronsted acids H₂O and HF are respectively:

1.  H₃O⁺ and H₂F⁺, respectively

2.  OH^- and H₂F⁺, respectively

3.  H₃O⁺ and F^-, respectively

4.  OH^- and F^-, respectively

pH of a saturated solution of $\mathrm{Ca}{\left(\mathrm{OH}\right)}_2$ is 9. The solubility product $\left({\mathrm{K}}_{\mathrm{sp}}\right)$ of $\mathrm{Ca}{\left(\mathrm{OH}\right)}_2$ is:

1.  $0.5\times {10}^{-10}$

2.  $0.5\times {10}^{-15}$

3.  $0.25\times {10}^{-10}$

4.  $0.125\times {10}^{-15}$

Which will make basic buffer:

1.  100 mL of 0.1 M HCl+100 mL of 0.1 M NaOH

2.  50 mL of 0.1 M NaOH+25 mL of 0.1 M CH₃COOH

3.  100 mL of 0.1 M CH₃COOH+100 mL of 0.1 M NaOH

4.  100 mL of 0.1 M HCl+200 mL of 0.1 M NH₄OH

The hydrogen ion concentration of a 10^-8 M HCl aqueous solution at 298 K (K_w = 10^-14) is :

1. $1.0\times {10}^{-6} M$

2. $1.0525\times {10}^{-7} M$

3. $9.525\times {10}^{-8} M$

4. $1.0\times {10}^{-8} M$

Which of the following pairs constitutes a buffer?

1. $HN{O}_2 and NaN{O}_2$

2. $NaOH and NaCl$

3. $HN{O}_3 and N{H}_{4}N{O}_3$

4. $HCl and KCl$

For the reaction, 
CH₄(g) + 2O₂(g) CO₂(g) + 2H₂O(l) 
Δ_rH = -170.8 kJ mol^-1 
Which of the following statements is not true?

1. At equilibrium, the concentration of $C{O}_2\left(g\right)$ and water (l) are not equal.

2. The equilibrium constant for the reaction is given by $K_p=\frac{\left[C{O}_2\right]}{\left[C{H}_4\right]\left[O_2\right]}$

3. Addition of $C{H}_4\left(g\right) or O_2\left(g\right)$ at equilibrium will cause a shift to the right

4. The reaction is exothermic

Which one of the following orders correctly represents the increasing acid strengths of the given acids?

1. $HOCl<HOClO<HOCl{O}_2<HOCl{O}_3$

2. $HOClO<HOCl<HOCl{O}_3<HOCl{O}_2$

3. $HOCl{O}_2<HOCl{O}_3<HOClO<HOCl$

4. $HOCl{O}_3<HOCl{O}_2<HOClO<HOCl$

Which ionic species has the greatest proton affinity to form stable compounds?

1. $H{S}^{-}$

2. $N{H}_2^{-}$

3. $F^{-}$

4. $l^{-}$

The following equilibrium constants are given : 
N₂ + 3H₂2NH₃; K₁ 
N₂ + O₂2NO; K₂ 
H₂ + 1/2O₂H₂O; K₃ 
The equilibrium constant for the oxidation of NH₃ by oxygen to give NO is:

1. $K_2{K}_3^3/K_1$

2. $K_2{K}_3^2/K_1$

3. $K_2^2{K}_3/K_1$

4. $K_1{K}_2/K_3$ 

A weak acid, HA, has a K_a of 1.00×10^-5. If 0.100 mole of this acid is dissolved in one litre of water, the percentage of acid dissociated at equilibrium is closest to :

1. 99.0%

2. 1%

3. 99.9%

4. 0.100%