Q 12-13-136JEE MainJEE Main 2017 (9 Apr)Easy
Imagine that a reactor converts all the given mass into energy and that it operates at a power level of $10^9$ watt. The mass of the fuel consumed per hour in the reactor will be: (velocity of light, $c$ is $3\times10^8\ \text{m s}^{-1}$)
Answer: (C) $4\times10^{-2}$ g
$$m = \frac{Pt}{c^2} = \frac{10^9\times3600}{9\times10^{16}} = 4\times10^{-5}\ \text{kg} = 4\times10^{-2}\ \text{g}$$
Solution by Sreeraj P, M.Sc Physics