Formaldehyde reacts with ammonia to give urotropine. The formula of urotropine is

$P$ is an optically active compound with molecular formula $C_6H_{12}O$. When $P$ is treated with $2,4-$dinitrophenylhydrazine,it gives a positive test. However,in the presence of Tollens reagent,$P$ gives a negative test. Predict the structure of $P$.

What is the product obtained in the reaction of acetaldehyde with semicarbazide?

The major product $Q$ of the following reaction scheme is:

What are $x$ and $y$ in the following reaction sequence?

In the given reactions,which one is $INCORRECT$?