An electron has mass $m$ and charge $e$. If it is accelerated from rest through a potential difference of $V$,what velocity will it attain?

The density of neutrons is of the order

Explain the discovery of the electron.

Arrange the following particles in the increasing order of their $e/m$ ratio: electron $(e)$,proton $(p)$,neutron $(n)$,and $\alpha$-particle $(\alpha)$.

The charge on an $\alpha -$ particle is ........... units.

The radius of a nucleus with mass number $A$ is given by $1.25 \times 10^{-13} \times A^{1/3} \ cm$. If the radius of the atom is $1 \ \mathring{A}$ and the mass number is $64$,calculate the fraction of the volume occupied by the nucleus.