Explanation

(a)
At constant temperature
$pV$ constant
On doubling $p$ and $V$ with constant $T$, the equilibrium constant $(K)$ will remain constant.
Pressure will never affect the value of $K$. It may result in the shifting of equilibrium, but not the equilibrium constant. By doubling the volume, the concentration of both reactants and products evenly became half. Therefore, over all there is no change in equilibrium constant value $(K)$.