Which of the following particles are constituents of the nucleus?

Two protons exert a nuclear force on each other. The distance between them is approximately:

The mass of a neutron is approximately the same as that of:

Assertion: Separation of isotopes is possible because of the difference in electron numbers of isotopes.
Reason: Isotopes of an element can be separated by using a mass spectrometer.

In the atomic scale,the weakest force in nature is

In the $_{88}Ra^{226}$ nucleus,there are