In the following reaction sequence, identify product ' Q ' ' and reagent ' R ' :

The alkyl halide reacts with the magnesium metal and formed the Grignard reagent. After that, Grignard reagent reacts with the carbon dioxide followed by hydrolysis. This gives the carboxylic acid as a product. The carboxylic acid is converted into the acid chloride by the reaction with ${\mathrm{SOCl}}_2$.

Reaction :-

Hence, $\text{Q}$ and $\mathrm{R}$ are .