Which of the following pairs of nuclei are isotones?

1. ${}_{34}{}^{74}\mathrm{Se},$ ${}_{31}{}^{71}\mathrm{Ca}$          

2. ${}_{42}{}^{92}\mathrm{Mo},$ ${}_{40}{}^{92}\mathrm{Zr}$

3. ${}_{38}{}^{81}\mathrm{Sr},$ ${}_{38}{}^{86}\mathrm{Sr}$             

4. ${}_{20}{}^{40}\mathrm{Ca},$ ${}_{16}{}^{32}\mathrm{S}$

Two nuclei fuse together to form a single nucleus as ${}_1{}^2\mathrm{A}+{}_1{}^2\mathrm{A}\to$ ${}_2{}^4\mathrm{B}$. If binding energy per nucleon of A and B are respectively x and y, then the energy released in the process is:

Fusion reaction takes place at a higher temperature because:

If a proton and anti-proton come close to each other and annihilate, how much energy will be released?

What is the respective number of $\alpha$ and $\beta$-particles emitted in the following radioactive decay?
\(X^{200}_{90}\rightarrow Y^{168}_{80}\)

If the nuclear density of the material of atomic mass 27 is \(3\rho _{0},\)$t$hen the nuclear density of the material of atomic mass 125 is:

1.  5${\rho }_0$

2.  3${\rho }_0$

3.  $\frac{5}{3}$${\rho }_0$

4.  ${\rho }_0$

${}_8{}^{19}\mathrm{O}$ $\to$ ${}_9{}^{19}\mathrm{F}$ $+$ $\mathrm{A}$ $+$ $\mathrm{B}$

In the given decay equation, A and B indicate:

After two alpha decays and four beta(-ve) decays, the atomic number:

Binding energy per nucleon of a fixed nucleus ^A$X$ is 8 MeV. It absorbs a neutron moving with kinetic energy 4 MeV and converts into Y emitting a photon of energy 2 MeV. The binding energy per nucleon of Y (in MeV) is:

1.  $\frac{8A+2}{A+1}$

2.  $\frac{8A-2}{A+1}$

3.  $\frac{8A-1}{A+1}$

4.  $\frac{8A}{A+1}$