In the reaction sequence $CH_3-C \equiv CH$ $\xrightarrow{CH_3MgBr, \text{Dry ether}} CH_4 + (A)$ $\xrightarrow[(i) \ CO_2]{(ii) \ H_2O/H^+} (B)$,$(B)$ will be

Which among the following reactions forms acid anhydride?

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:

Which among the following compounds is obtained when ethanenitrile is acid hydrolysed?

Describe the method for the preparation of carboxylic acids from nitrogen-containing compounds (nitriles) with suitable examples.

Considering the above chemical reaction,identify the product $X$.