$A$ nucleus ${}^{220}X$ at rest decays by emitting an $\alpha$-particle. If the kinetic energy of the daughter nucleus is $0.2 \, MeV$,the $Q$-value of the reaction is ........ $MeV$.

In a nuclear fission process,a high mass nuclide $(A \approx 236)$ with binding energy $7.6 \ MeV/\text{nucleon}$ dissociates into two middle mass nuclides $(A \approx 118)$,each having a binding energy of $8.6 \ MeV/\text{nucleon}$. The energy released in the process is $MeV$.

Consider the fission of $_{92}^{238} U$ by fast neutrons. In one fission event,no neutrons are emitted and the final end products,after the beta decay of the primary fragments,are $_{58}^{140} Ce$ and $_{44}^{99} Ru$. Calculate the $Q$-value for this fission process. The relevant atomic and particle masses are:
$m(_{92}^{238} U) = 238.05079 \; u$
$m(_{58}^{140} Ce) = 139.90543 \; u$
$m(_{44}^{99} Ru) = 98.90594 \; u$
$m(_{0}^{1} n) = 1.008665 \; u$

In the options given below, let $E$ denote the rest mass energy of a nucleus and $n$ a neutron. The correct option is:

The minimum kinetic energy needed by an alpha particle to cause the nuclear reaction ${ }_{7}^{16} N +{ }_{2}^{4} He \rightarrow{ }_{1}^{1} H +{ }_{8}^{19} O$ in a laboratory frame is $n$ (in $MeV$). Assume that ${ }_{7}^{16} N$ is at rest in the laboratory frame. The masses of ${ }_{7}^{16} N, { }_{2}^{4} He, { }_{1}^{1} H$ and ${ }_{8}^{19} O$ can be taken to be $16.006 \ u, 4.003 \ u, 1.008 \ u$ and $19.003 \ u$,respectively,where $1 \ u = 930 \ MeV/c^2$. The value of $n$ is. . . . .

What is nuclear energy?