On what factor does the intensity (brightness) of spectral lines depend?

Fill in the blanks given below:
$(i)$ The picture on the television screen is visible due to the presence of .......... on the screen.
$(ii)$ In the presence of electric and magnetic fields,cathode rays are known as .......... .
$(iii)$ The measurement of the $e/m_e$ ratio for electrons was performed by the scientist .......... .
$(iv)$ In a cathode ray tube,the greater the magnitude of the charge on the particles,the .......... the deflection of the particles.

The ratio of specific charge of a proton and an $\alpha$-particle is

$A$ neutral atom (Atomic number $Z > 1$) consists of:

Who discovered the proton and the neutron?

Which one of the following pairs is not correctly matched?