Benzaldehyde on heating with concentrated $NaOH$ gives:

Identify the products $(A)$ and $(B)$ from the given structures $P, Q, R$.

Which of the following carbonyl compounds gives both Fehling's test and iodoform test?

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....

For making a distinction between $2$-pentanone and $3$-pentanone,the reagent to be employed is

Identify the product $(A)$ and the name of the reaction for the given transformation: