What is $A$ in the following reaction?

In the reaction sequence $CH_3CONH_2$ $\xrightarrow{?} CH_3CN$ $\xrightarrow{\text{reduction}} CH_3CH_2NH_2$,which dehydrating agent is used in the first step?

Identify '$B$' in the reaction: $\text{Acetamide}$ $\xrightarrow{\Delta, P_2O_5} A$ $\xrightarrow{4H} B$

The diazonium salts are the reaction products in the presence of excess of mineral acid with nitrous acid and:

The conversion of propan$-1-$ol to $n-$butylamine involves the sequential addition of reagents. The correct sequential order of reagents is:

Identify $X$ and $Y$ in the following sequence:
$C_2H_5Br$ $\xrightarrow{X} \text{product}$ $\xrightarrow{Y} C_3H_7NH_2$