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. $0.125\times {10}^{-15}$

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.

Which composition will make the basic buffer?

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. $1.0\times {10}^{-8}$ $M$

The following pair constitutes a buffer is:

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?
 

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. $HOCl{O}_3<HOCl{O}_2<HOClO<HOCl$

The ionic species that has the greatest proton affinity to form stable compound is:

1. $H{S}^{-}$

2. $N{H}_2^{-}$

3. $F^{-}$

4. $l^{-}$

The following equilibrium constants are given: 
N₂ + 3H₂ ⇌ 2NH₃; K₁ 
N₂ + O₂ ⇌ 2NO; K₂ 
H₂ + 1/2O₂ ⇌ H₂O; 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%