Which of the following species has bond order different from that in CO?

Question

$\begin{array}{1 1}(a)\;NO^+\\(b)\; NO^-\\(c)\; CN^-\\(d)\; N_2\end{array}$

Answer 1

The CO bond order is 3, where as $NO^-$ bond order is 2

Hence (b) is the correct answer.