Electric Charges and Fields — Physics STD 12 Science — Question

CONCEPT:
Strong nuclear force: The strong attractive force which binds together the protons and neutrons in a nucleus is called a strong nuclear force.
$-$ This force cannot be an electrostatic force because positively charged protons strongly repel each other at such a small separation of the order $10^{-15} m$.
$-$ This strong nuclear force is the strongest of all the fundamental forces, about $100$ times stronger than the electromagnetic force.
Important properties of the strong nuclear force:
$-$ It is the strongest interaction known in nature, which is about $1038$ times stronger than the gravitational force.
$-$ It is a short-range force that operates only over the size of the nucleus $\left(=10^{-15} m\right)$.
$-$ It is basically an attractive force but becomes repulsive when the distance between the nucleons becomes less than $0.5$ fermi ( $1$ fermi $=10^{-15} m ).$
$-$ It varies inversely with some higher power $(> 2)$ of distance.
$-$ It is a non-central and non$-$conservative force.
From the above, it is clear that the force between a neutron and a proton inside the nucleus is only nuclear attractive.