The above conversion can be achieved by:

Complete reaction of acetaldehyde with excess formaldehyde,upon heating with conc. $NaOH$ solution,gives $P$ and $Q$. Compound $P$ does not give Tollens' test,whereas $Q$ on acidification gives positive Tollens' test. Treatment of $P$ with excess cyclohexanone in the presence of catalytic amount of $p$-toluenesulfonic acid $(PTSA)$ gives product $R$. Sum of the number of methylene groups $(-CH_2-)$ and oxygen atoms in $R$ is....

The major products of the following reaction are:

Arrange the following in increasing order of their reactivity for nucleophilic addition reaction:

Urotropine is

Given below are two statements:
Statement $I$: $2, 6$-diethylcyclohexanone and $6$-methyl-$2$-$n$-propylcyclohexanone are metamers.
Statement $II$: $2, 2, 6, 6$-tetramethylcyclohexanone exhibits keto-enol tautomerism.