Are neutrons present in all atomic nuclei? Explain.

Positronium is the name given to an atom-like combination formed between

Who discovered the neutron?

Rutherford's $\alpha$-particle scattering experiment is related to the size of the .....

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

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.