Formalin is the commercial name of

An organic compound $(A)$ with molecular formula $C_8H_8O$ forms an orange-red precipitate with $2,4-DNP$ reagent and gives a yellow precipitate on heating with iodine in the presence of sodium hydroxide. It neither reduces Tollens' or Fehlings' reagent,nor does it decolourise bromine water or Baeyer's reagent. On drastic oxidation with chromic acid,it gives a carboxylic acid $(B)$ having molecular formula $C_7H_6O_2$. Identify the compounds $(A)$ and $(B)$ and explain the reactions involved.

Which reagent turns pink in the presence of an aldehyde?

Write about the boiling points of aldehydes and ketones.

The suitable reagents $X$ and $Y$,respectively,in the following reactions are:

An organic compound $CH_3-CH=CH-CH_2-CHO$ is taken in two different containers $A$ and $B$. Sample in $A$ is treated with $H_2 / Ni$ forming new compound $P$. Sample in $B$ is treated with $LiAlH_4$ and hydrolyzed further forming new compound $Q$. Identify $P$ and $Q$.