Who discovered the neutron?

The masses of an electron,a proton and a neutron respectively will be in the ratio

Cathode rays are made up of

Fill in the blanks:
$(i)$ When amber or ebonite is rubbed with silk or fur,it produces $......$.
$(ii)$ In a discharge tube,the stream of particles flows from cathode to anode. This is called $......$.
$(iii)$ In a cathode ray tube,a coating of $......$ is applied as a fluorescent material.
$(iv)$ $A$ television picture tube is a type of $......$ tube.

Which particle cannot be accelerated?

Cathode rays have