What is the ratio of the mass of an electron to the mass of a proton?

The mass of an electron is ......... compared to the mass of the lightest nucleus.

The relationship between the radius of the nucleus $(R)$ and the mass number $(A)$ is given by .......

Which of the following particles cannot be accelerated by an electric or magnetic field?

Experimental evidence for the existence of the atomic nucleus comes from

Fill in the blanks:
$(i)$ For the discovery of neutrons,$\alpha$-particles were bombarded on a thin sheet of ......... .
$(ii)$ For the $\alpha$-particle scattering experiment,Rutherford used a gold foil of thickness ......... .
$(iii)$ The radius of an atom is approximately ......... and the radius of the nucleus is ......... .
$(iv)$ The entire positive charge of an atom is concentrated in a very small region,which is called ......... .