The number of electrons in the nucleus of $^{12}C$ is

Explain the discovery of protons.

Neutrons are found in atoms of all elements except in

An atom is defined as :

The charge on a positron is equal to the charge on which one of the following?

The nucleus of an atom can be assumed to be spherical. The radius of the nucleus of mass number $A$ is given by $1.25 \times 10^{-13} \times A^{1/3} \ cm$. The radius of the atom is $1 \ \mathring{A}$. If the mass number is $64$,then the fraction of the atomic volume that is occupied by the nucleus is: