o Degenerate orbital means orbital having same energies. And the energy of an electron in the multi-electron system of atoms depends on the principal quantum number (which is the main shell,n) and the azimuthal quantum number(which is the sub-shell, l ) as well.

o Hence , electrons which are present in the same main shell and the same sub-shells as well will have the same energies and this means they should have equal n and l values too, which is the case for

(i) (a) n = 3, l = 2, m_i = –2, m_s = - 1/2and (b) n = 3, l = 2, m_i = –1, m_s= − 1/2and

(iv) (a) n = 3, l = 2, m_I = +2, m_s = − 1/2,(b) n = 3, l = 2, m_I = +2, m_s = + 1/2as well where n and l values are equal.

The other 2 options (ii) (a) n = 3, l = 1, m_i = 1, m_s = +1/2(b) n = 3, l = 2, m_l = 1, m_s = + 1/2

And (iii) (a) n = 4, l = 1, m_I = 1, m_s = + 1/2(b) n = 3, l = 2, m_I = 1, m_s = + 1/2are in correct because the electrons present in there are not having degenerate orbitals.