$\alpha$-particles can be detected using

Which is the correct statement about a proton?

Who discovered the proton and the neutron?

The nucleus and an atom can be assumed to be spherical. The radius of the nucleus of mass number $A$ is given by $R_n = 1.25 \times 10^{-13} \times A^{1/3} \, \text{cm}$. The atomic radius is $1 \, \mathring{A}$. If the mass number is $64$,the fraction of the atomic volume that is occupied by the nucleus is:

The size of the nucleus is measured in

The average distance of an electron in an atom from its nucleus is of the order of: