Which of the following substances reacts with $NH_3$ to form an amide or an amide-like derivative?

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

Grignard reagents do not give carbonyl compounds with :

Reaction of acetaldehyde with $HCN$ followed by hydrolysis gives a compound which shows

Statement-$I$: Most carboxylic acids exist as dimers in vapour phase or in aprotic solvents due to intermolecular hydrogen bonding.
Statement-$II$: Higher carboxylic acids are practically insoluble in water due to the increased hydrophobic interaction of the hydrocarbon part.

Which will form lactone on treatment with $NaOH$?