Which among the following is dicarboxylic acid?

Identify ' $B$ ' in the following sequence of reactions.

Acetic acid $\xrightarrow[\Delta]{\text { Thionyl chloride }} \mathrm{A} \xrightarrow{\text { Ammonia }} \mathrm{B}$

Which among the following has highest boiling point?

Identify the product formed in the following reaction. $\left(\mathrm{CH}_3 \mathrm{CO}\right)_2 \mathrm{O} \xrightarrow{\mathrm{H}_2 \mathrm{O}}$ Product