b
\(C_2^{2 - } - {\sigma _{1s}}2{\sigma ^*}_{1s}2{\sigma _{2s}}2{\sigma ^*}_{2{s^2}}[{\pi _{2p_x^2}} = {\pi _2}p_y^2]{\sigma _{2p_z^2}}\)

\(B.O = \frac{{10 - 4}}{2} = 3\) (diamagnetic)

\(N_2^{2 - } - {\sigma _{1s}}2{\sigma ^*}_{1s}2{\sigma _{2s}}2{\sigma ^*}_{2{s^2}}[{\pi _{2p_x^2}} = {\pi _2}p_y^2]{\sigma _{2p_z^2}}[{\pi _{2p_x^1}} = {\pi ^*}_{2p_y^1}]\)

\(B.O = \frac{{10 - 6}}{2} = 2\) (paramagnetic)

\(O_2^{2 - } - {\sigma _{1s}}2{\sigma ^*}_{1s}2{\sigma _{2s}}2{\sigma ^*}_{2s}2{\sigma _{2p_z^2}}[{\pi _{2p_x^2}} = {\pi _2}p_y^2]\,[{\pi _{2p_x^2}} = {\pi ^*}_2p_y^2]\)

\(B.O = \frac{{10 - 8}}{2} = 1\) (diamagnetic)

\({O_2} - {\sigma _{1s}}2{\sigma ^*}_{1s}2{\sigma _{2s}}2{\sigma ^*}_{2s}2{\sigma _{2p_z^2}}\,[{\pi _{2p_x^2}} = {\pi _2}p_y^2]\,[{\pi _{2p_x^2}} = {\pi ^*}_2p_y^2]\)

\(B.O = \frac{{10 - 6}}{2} = 2\) (paramagnetic)