Match the given ionisation constant values with the corresponding acids.

$$ \begin{array}{lll} \hline \text { A. } & \mathrm{HI} & \text { (i) } 3.2 \times 10^9 \\ \hline \text { B. } & \mathrm{HF} & \text { (ii) } 3.5 \times 10^{-4} \\ \hline \text { C. } & \mathrm{HCl} & \text { (iii) } 1.3 \times 10^6 \\ \hline \text { D. } & \mathrm{HBr} & \text { (iv) } 1.0 \times 10^9 \\ \hline \end{array} $$

$$ \text { The correct match is } $$

With reference to the redox properties of hydrogen peroxide $\left(\mathrm{H}_2 \mathrm{O}_2\right)$, which of these reactions are feasible?

(i) $2 \mathrm{Fe}^{2+} 2 \mathrm{H}^{+}+\mathrm{H}_2 \mathrm{O}_2 \longrightarrow 2 \mathrm{Fe}^{3+}+2 \mathrm{H}_2 \mathrm{O}$

(ii) $2 \mathrm{MnO}_4^{-}+6 \mathrm{H}^{+}+5 \mathrm{H}_2 \mathrm{O}_2 \longrightarrow 2 \mathrm{Mn}^{2+}+8 \mathrm{H}_2 \mathrm{O}+5 \mathrm{O}_2$

(iii) $2 \mathrm{Fe}^{2+}+\mathrm{H}_2 \mathrm{O}_2 \longrightarrow 2 \mathrm{Fe}^{3+}+2 \mathrm{OH}^{-}$

(iv) $2 \mathrm{MnO}_4^{-}+3 \mathrm{H}_2 \mathrm{O}_2 \longrightarrow 2 \mathrm{MnO}_2+2 \mathrm{H}_2 \mathrm{O} +3 \mathrm{O}_2+2 \mathrm{OH}^{-} $

Which halide of alkaline earth metals is covalent in nature and can be soluble in organic solvent, such as ethanol?

An aqueous solution of borax is