The size of the nucleus is of the order of

The radius of a nucleus with mass number $A$ is given by $1.25 \times 10^{-13} \times A^{1/3} \ cm$. If the radius of the atom is $1 \ \mathring{A}$ and the mass number is $64$,calculate the fraction of the volume occupied by the nucleus.

State whether the following statements are true or false:
$(i)$ Faraday's electrolysis experiments and cathode ray discharge tube experiments prove that protons are located in the nucleus of the atom,while electrons are located outside the nucleus.
$(ii)$ In the year $1887$,Goldstein discovered the proton.
$(iii)$ In the year $1932$,the neutron was discovered by Chadwick.
$(iv)$ The first atomic model was proposed by Thomson.

The density of neutrons is of the order

Write the formulas for calculating Coulombic forces and gravitational forces.

Among the following,the correct statement about the cathode ray discharge tube is: