What is the initial product obtained from the hydrolysis of cyanide?

Identify product $C$ in the following conversion sequence: $m$-Hydroxybenzaldehyde $\xrightarrow[\text{Protection of } -OH \text{ group}]{C_6H_5CH_2Cl} A$ $\xrightarrow{[O]} B$ $\xrightarrow{\text{deprotection}} C$.

Which one of the following reactions will not yield propionic acid?

If we use pyrene $(CCl_4)$ in the Riemer-Tiemann reaction in place of chloroform,the product formed is

Which among the following reactions forms acid anhydride?

Write a note on the preparation of carboxylic acid from alkyl benzene.