Question

What is the maximum number of electron in a $d-$subshell with same spin?

Answer 1

Maximum number of electrons in $0d-$subshell, with same spin, can be $5$.

According to Pauli's exclusion Principle, "an orbital can have opposite spin". $d-$subshell has five orbitals. So, it can contain maximum $10$ electrons, five of which should be of same spin.