(d) Escape velocity from the earth’s surface is $11.2\ km/sec$
So, $v_{rms} = v_{escape} = \sqrt{\frac{3RT}{M}} \Rightarrow T = \frac{\left( v_{escape} \right)^{2} \times M}{3R}$
$= \frac{\left( 11.2 \times 10^{3} \right)^{2} \times (2 \times 10^{- 3})}{3 \times 8.31} = 10063K$