Question

How many of these molecules are diamagnetic and have bond order more than $2$
$O_{2}^{2+}, C O, \bar{C} N, N O, N O^{+}, N_{2}, O_{2}^{+}, N_{2}^{2-}, O_{2}^{2-}$

Answer 1

$O_{2}^{2+}, C O, \bar{C} N, N O^{+}, N_{2}$ have bond order $3$ and are diamagnetic also.
$NO , O _{2}^{+}$have bond order $2.5$ but are paramagnetic.
$N_{2}^{2-}, O_{2}^{2-}$ have bond order $ 2 $ and $1$ respectively.