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

Highly energetic electrons are bombarded on a target of an element containing $30$ neutrons. The ratio of radii of nucleus to that of Helium nucleus is ${14^{1/3}}$. The atomic number of nucleus will be

Define nuclear force.

The mass number of nucleus having radius equal to half of the radius of nucleus with mass number $192$ is:

Consider the following statements :

$A.$ Atoms of each element emit characterstics spectrum.

$B.$ According to Bohr's Postulate, an electron in a hydrogen atom, revolves in a certain stationary orbit.

$C.$ The density of nuclear matter depends on the size of the nucleus.

$D.$ A free neutron is stable but a free proton decay is possible.

$E.$ Radioactivity is an indication of the instability of nuclei.

Choose the correct answer from the options given below 

In a nuclear reaction, which of the following is conserved