(d) Given$k_{p} = 2k_{Q}$
By stretched spring gain get energy
$E = \frac{1}{2}kx^{2}\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ (\because F = kx)$
OR $E = \frac{1}{2}\ \frac{F^{2}}{K}$
$\because For\ spring\ P$
$E_{P} = \frac{1}{2}\ \frac{F^{2}}{K_{P}}$
$\because For\ spring\ Q$
$E_{Q} = \frac{1}{2}\ \frac{F^{2}}{K^{Q}}$
$\frac{E_{P}}{E_{Q}} = \frac{K_{Q}}{K_{P}} = \frac{1}{2}$
$E_{P} = \frac{E_{Q}}{2} = \frac{E}{2}$