Mention the disadvantages of the nuclear reactor.

Which of the following are suitable for the fusion process?

What is a nuclear chain reaction? Explain the difficulties and their removal for its successful operation.

$A$ heavy nucleus $N$,at rest,undergoes fission $N \rightarrow P+Q$,where $P$ and $Q$ are two lighter nuclei. Let $\delta=M_N-M_P-M_Q$,where $M_P, M_Q$ and $M_N$ are the masses of $P, Q$ and $N$,respectively. $E_P$ and $E_Q$ are the kinetic energies of $P$ and $Q$,respectively. The speeds of $P$ and $Q$ are $v_P$ and $v_Q$,respectively. If $c$ is the speed of light,which of the following statement$(s)$ is(are) correct?
$(A)$ $E_P+E_Q=c^2 \delta$
$(B)$ $E_P=\left(\frac{M_P}{M_P+M_Q}\right) c^2 \delta$
$(C)$ $\frac{v_P}{v_Q}=\frac{M_Q}{M_P}$
$(D)$ The magnitude of momentum for $P$ as well as $Q$ is $c \sqrt{2 \mu \delta}$,where $\mu=\frac{M_P M_Q}{M_P+M_Q}$

The energy released by the fission of one uranium atom is $200 MeV$. The number of fissions per second required to produce $3.2 W$ of power is (Take $1 eV = 1.6 \times 10^{-19} J$).

When a slow neutron goes sufficiently close to a ${U^{235}}$ nucleus,then the process that takes place is