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

What percentage of mass is converted into energy during nuclear fission?

Which of the following is the best neutron moderator compared to all others?

In a nuclear reactor,the function of the moderator is to decrease

$200\, MeV$ of energy may be obtained per fission of ${U^{235}}$. $A$ reactor is generating $1000\, kW$ of power. The rate of nuclear fission in the reactor is

The isotope ${}_{5}^{12}B$ having a mass $12.014 \text{ u}$ undergoes $\beta$-decay to ${}_{6}^{12}C$. ${}_{6}^{12}C$ has an excited state of the nucleus $({}_{6}^{12}C^*)$ at $4.041 \text{ MeV}$ above its ground state. If ${}_{5}^{12}B$ decays to ${}_{6}^{12}C^*$, the maximum kinetic energy of the $\beta$-particle in units of $\text{MeV}$ is ($1 \text{ u} = 931.5 \text{ MeV}/c^2$, where $c$ is the speed of light in vacuum).