How much energy is released by the fusion of four hydrogen atoms to form a helium nucleus (in $MeV$)?

What is used as a moderator in a nuclear reactor?

The energy released per fission of uranium-$235$ is about $200 \, MeV$. $A$ reactor using $U-235$ as fuel is producing $1000 \, kW$ power. The number of $U-235$ nuclei undergoing fission per second is approximately:

Find the value of $x$ and $y$ in the following nuclear reaction:
${}_{92}^{235} U + {}_{0}^{1} n \rightarrow {}_{x}^{133} Sb + {}_{41}^{y} Nb + 4 {}_{0}^{1} n$

$A$ nuclear reactor provides a power of $300 \, MW$. If the fission of one uranium nucleus ${U^{235}}$ releases $170 \, MeV$ of energy,how many nuclei undergo fission in $1 \, h$?

In an $\alpha -$ decay,the kinetic energy of the $\alpha -$ particle is $48 \ MeV$ and the $Q$ value of the reaction is $50 \ MeV$. The mass number of the mother nucleus is (assume that the daughter nucleus is in the ground state).