In a reaction,

$$ \left(\mathrm{CH}_3\right)_2 \mathrm{CHMgBr}+\mathrm{CO}_2 \xrightarrow[\text { ether }]{\text { dry }} \mathrm{A} \xrightarrow[\text { dilHCl }]{\mathrm{H} . \mathrm{OH}} \mathrm{~B} \text {. } $$

Find the product ' B ' of above reaction.

Identify the reagent used in the following reaction.

Benzoic acid $\xrightarrow{\text { Reagent }}$ Benzoyl chloride + Phosphorus oxychloride + Hydrogen chloride

Identify the product ' B ' in following reaction.

Dry ice $\xrightarrow[\text { dry ether }]{\mathrm{CH}_3 \mathrm{MgBr}} \mathrm{A} \xrightarrow{\mathrm{H}_3 \mathrm{O}^{+}} \mathrm{B}$

Which from following compounds is obtained when acetamide is warmed with bromine and excess conc. $\mathrm{KOH}_{(\mathrm{aq})}$ solution?