The neutrino has:

Which of the following particles is represented by the symbol $\alpha$?

Proton is

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

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 ......... .

The minimum real charge on any particle which can exist is