Formic acid is obtained when

What is $P$ in the following reaction?

Write the method of preparation of carboxylic acid from acyl halides and anhydride compounds.

Consider the following reactions. From these reactions,which reaction will give carboxylic acid as a major product?
$(A)$ $R-C \equiv N \xrightarrow[(i) H^{+}/H_2O]{\text{mild condition}} R-CONH_2$
$(B)$ $R-MgX \xrightarrow[(ii) H_3O^{+}]{\text{(i) } CO_2} R-COOH$
$(C)$ $R-C \equiv N \xrightarrow[(ii) H_3O^{+}]{\text{(i) } SnCl_2/HCl} R-CHO$
$(D)$ $R-CH_2-OH \xrightarrow{PCC} R-CHO$
$(E)$ $\text{Benzoyl chloride} \xrightarrow[(ii) Br_2/H_2O]{\text{(i) } H_2/Pd-BaSO_4} \text{Benzoic acid}$
Choose the correct answer from the options given below:

In the presence of an acid,the hydrolysis of methyl cyanide gives:

Identify $A$ and $B$ in the following reactions: $R-CHO \xrightarrow{A} R-CH_2OH \xleftarrow{B} R-COOH$