Question

A pairing of nucleons of opposite spins is favored inside a nucleus because:

• A. According to Pauli's exclusion principle no two nucleons can be in the same quantum state
• B. According to Pauli's exclusion principle no two nucleons can be in the same state of spin
• C. The nuclear force between two nucleons of same spin is repulsive
• D. All of the above

Answer 1

The correct option is A According to Pauli's exclusion principle no two nucleons can be in the same quantum state

Pauli's exclusion principle for nucleus is the same as that for the electrons.
It states that no two nucleons can be in the same quantum state. This doesn’t imply that no two nucleons can be in the same state of spin, they can be. It just means that all the quantum numbers for any two nucleons can't be the same.
As far as force is concerned, the nuclear force is spin dependent but it's not repulsive between the two nucleons of same spin. It's still attractive