In the gaseous phase reaction : $A_2(g) \to B(g) +\bigg( \large\frac{1}{2}$$C(g)$ the increase in pressure from 100 mm to 120 mm is noticed in 5 minute. The rate of disappearance of $A_2$ in mm $min^{-1}$ is

Question

$\begin{array}{1 1} 4 \\ 8 \\ 16 \\ 2 \end{array}$