Write the definitions of isotopes, isobar and isotone. 

The nuclear radius is given by $R=r_0 A^{1 / 3}$, where $r_0$ is constant and $A$ is the atomic mass number. Then, the nuclear mass density of $U^{238}$ is

Atomic weight of boron is $10.81$ and it has two isotopes $_5{B^{10}}$ and $_5{B^{11}}$. Then ratio of  $ _5{B^{10}}{\,:\,_5}{B^{11}} $ in nature would be

The neutron was discovered by

If radius of the $^{27}_{13}Al$ nucleus is taken to be $R_{Al}$, then the radius of $^{125}_{53}Te$ nucleus is nearly

Assertion : Neutrons penetrate mater more readily as compared to protons.

Reason : Neutrons are slightly more massive than protons.