Which of the following is used as a moderator in nuclear reactors?

The fission of a $_{92}U^{235}$ nucleus releases $200 \, MeV$ of energy. Find the rate of fission of $_{92}U^{235}$ required to operate a reactor at a constant power of $5 \, W$.

The example of nuclear fusion is

Which of the following isotopes is used for the treatment of cancer?

$A$ star has $10^{40}$ deuterons. It produces energy via the processes:
$_1H^2 + _1H^2 \to _1H^3 + p$
$_1H^2 + _1H^3 \to _2He^4 + n$
If the average power radiated by the star is $10^{16} \ W$, the deuteron supply of the star is exhausted in a time of the order of:
Given:
Mass of $_1H^2 = 2.014 \ amu$
Mass of $_2He^4 = 4.001 \ amu$
Mass of proton = $1.007 \ amu$
Mass of neutron = $1.008 \ amu$

The mechanism of the hydrogen bomb is based on