Identify the correct reagents for the given reaction sequence:

Two aliphatic aldehydes $P$ and $Q$ react in the presence of aqueous $K_2CO_3$ to give compound $R$,which upon treatment with $HCN$ provides compound $S$. On acidification and heating,$S$ gives the product shown below:
$1.$ The compounds $P$ and $Q$ respectively are:
$2.$ The compound $R$ is:
$3.$ The compound $S$ is:
Give the answer for questions $1$,$2$ and $3$.

Which reagent is used to distinguish Acetophenone and Benzophenone?

The product formed when hydroxylamine $(NH_2OH)$ condenses with a carbonyl compound is called:

An organic compound $A$ has the molecular formula $C_3H_6O$. It gives the iodoform test. When it is saturated with $HCl$,it gives a compound $B$ with the molecular formula $C_9H_{14}O$. What are $A$ and $B$ respectively?

In the above reaction,product $(B)$ is: