(b) $Q \propto T^{4} \Rightarrow \frac{Q_{1}}{Q_{2}} = \frac{T_{1}^{4}}{T_{2}^{4}} \Rightarrow T_{2}^{4} = \left( \frac{E_{2}}{E_{1}} \right)T_{1}^{4}$
$\Rightarrow T_{2}^{4} = \frac{1}{16} \times (1000)^{4} = \left( \frac{1000}{2} \right)^{4}$
$\Rightarrow T_{2} = 500K$