(c)
$\left( NH_{4} \right)_{2}SO_{4} \longrightarrow 2NH_{3} + H_{2}O + SO_{3}$
$3NH_{3} + 2HCl \longrightarrow 2NH_{4}Cl$
$\left( NH_{4} \right)_{2}SO_{4} \equiv 2NH_{3} \equiv 2HCl$
132 g 73g
73g$HCl \equiv 132g\left( NH_{4} \right)_{2}SO_{4}$
292 $g\ HCl \equiv \frac{132 \times 292}{73}g\left( NH_{4} \right)_{2}SO_{4}$
$= 528\ g\left( NH_{4} \right)_{2}SO_{4}$