The major product $'P'$ formed in this reaction is:

$A$ compound gives a positive test with $I_2/NaOH$ and is extracted from benzene by saturated $NaHSO_3$. It may be

An organic compound $P$ having molecular formula $C_6H_6O_3$ gives a ferric chloride test and does not have an intramolecular hydrogen bond. The compound $P$ reacts with $3$ equivalents of $NH_2OH$ to produce oxime $Q$. Treatment of $P$ with excess methyl iodide in the presence of $KOH$ produces compound $R$ as the major product. Reaction of $R$ with excess iso-butylmagnesium bromide followed by treatment with $H_3O^{+}$ gives compound $S$ as the major product. The total number of methyl $(-CH_3)$ groups in compound $S$ is . . . .

When the compound $CH_3COCH_2CH_2CH_2CH_2CHO$ undergoes intramolecular aldol condensation,the major product formed is $:$

The product $(4)$ in the given reaction sequence is:

The product formed by the reaction of an aldehyde with a primary amine is