The most stable particle in the Baryon group is

Which physical quantity is measured in barn?

The distance between two nucleons for which the potential energy is minimum, is (in $fm$)

The size of the nucleus is of the order of:

In a triclinic crystal system,which of the following conditions is true?

Consider the following statements:
$I$. All isotopes of an element have the same number of neutrons.
$II$. Only one isotope of an element can be stable and non-radioactive.
$III$. All elements have isotopes.
$IV$. All isotopes of carbon can form chemical compounds with oxygen-$16$.
Choose the correct option regarding an isotope.