(b)
$K_{c} = \frac{\lbrack HI\rbrack^{2}}{\left\lbrack H_{2} \right\rbrack\lbrack I_{2}\rbrack}$
$\therefore 64 = \frac{x^{2}}{0.03 \times 0.03}$
$\therefore x^{2} = 64 \times 9 \times 10^{- 4}$
or, $x = 8 \times 3 \times 10^{- 2}$
$x$ is the amount of HI
At equilibrium, amount of $I_{2}$ will be
$0.30 - 0.24 = 0.06$