Which of the following on reaction with Grignard reagent followed by hydrolysis forms a tertiary alcohol?

Which of the following aldehydes is less reactive towards nucleophilic addition reaction?

An optically active alkyl bromide $C_4H_9Br$ reacts with ethanolic $KOH$ to form major compound $[A]$,which reacts with bromine to give compound $[B]$. Compound $[B]$ reacts with ethanolic $KOH$ and sodamide to give compound $[C]$. One molecule of water adds to compound $[C]$ on warming with mercuric sulphate and dilute sulphuric acid at $333 \text{ K}$ to form compound $[D]$. The functional group in compound $[D]$ will be confirmed by:

Bromination of $PhCOMe$ in acetic medium produces mainly

$p$-cresol reacts with chloroform in an alkaline medium to give compound $A$,which adds hydrogen cyanide to form compound $B$. The latter,on acidic hydrolysis,gives a chiral carboxylic acid. The structure of the carboxylic acid is:

Identify $P$ and $Q$ respectively of the following reaction.