What is the product obtained by the partial hydrolysis of acetonitrile with cold concentrated $HCl$?

Which of the following compounds is obtained when $R-CHO$ is treated with dilute nitric acid?

Acid $D$ formed in the reaction sequence is:

In the given reaction,the product $P$ is:

An alkyl bromide $X$ $(C_5H_{11}Br)$ undergoes hydrolysis in a two-step mechanism. $X$ is converted to a Grignard reagent and then reacted with $CO_2$ in dry ether followed by acidification to give $Y$. What is $Y$?

The reaction of toluene with acidic $KMnO_4$ gives ..........