The radius of an atom is about

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.

$A$ particle having the same charge and $200$ times greater mass than that of an electron is:

An atom is defined as :

The minimum real charge on any particle which can exist is

The average distance of an electron in an atom from its nucleus is of the order of: