Which among the following is a pair of monocarboxylic acids?

Identify the overall oxidation reaction that occurs in lead storage cell during discharge.

What is the change in oxidation number of selenium in the following redox reaction?

$$\mathrm{SeO}_{3(\text { (a) })}^{2-}+\mathrm{Cl}_{2(\mathrm{~g})}+2 \mathrm{OH}^{-} \longrightarrow \mathrm{SeO}_{4(\text { (a) })}^{2-}+2 \mathrm{Cl}_{(\text {(a) })}^{-}+\mathrm{H}_2 \mathrm{O}$$

A buffer solution is prepared by mixing equimolar acetic acid and sodium acetate. If '$$\mathrm{K}_d$$' of acetic acid is $$1.78 \times 10^{-5}$$, find the $$\mathrm{pH}$$ of buffer solution.