(a)
In presence of dil. HCl, acetamide is hydrolysed by boiling, the product obtained is acetic acid $\left( CH_{3}COOH \right).$
$CH_{3}CONH_{2} + H_{2}O \rightarrow CH_{3}COOH + NH_{3}$
$CH_{3}CONH_{2} + H_{2}O + HCl \rightarrow CH_{3}COOH + NH_{4}Cl$