Two nucleons are at a separation of $1 \times {10^{ – 15}}m$. The net force between them is ${F_1}$, if both are neutrons, ${F_2}$ if both are protons and ${F_3}$ if one is a proton and other is a neutron. In such a case

Assume that the nuclear binding energy per nucleon $(B/A)$ versus mass number $(A)$ is as shown in the figure. Use this plot to choose the correct choice $(s)$ given below

$(A)$ Fusion of two nuclei with mass numbers lying in the range of $1 < A < 50$ will release energy

$(B)$ Fusion of two nuclei with mass numbers lying in the range of $51 < A < 100$ will release energy

$(C)$ Fission of a nucleus lying in the mass range of $100 < A < 200$ will release energy when broken into two equal fragments

$(D)$ Fission of a nucleus lying in the mass range of $200 < A < 260$ will release energy when broken into two equal fragments

The ratio of radii of nuclei $_{13}A{l^{27}}$ and $_{52}{X^A}$ is $3 : 5$. The number of neutrons in the nuclei of $X$ will be

Ratio of nuclear radii of ${ }^{135} Cs$ to ${ }^{40} Ca$ is

What is the nucleus of an atom ?