Four diatomic species are listed below in different sequences....

$$\begin{aligned} & \text{Key Idea : Bond order }=\frac{N_b-N_a}{2} \\ & \mathrm{He}_2^{+}:(\sigma 1 s)^2\left(\sigma^* 1 s\right)^1 \\ & \text{ Bond order }=\frac{2-1}{2}=\frac{1}{2} \\ & \mathrm{C}_2^{2-}: \\ & K K(\sigma 2 s)^2(\sigma * 2 s)^2\left(\pi 2 p_x\right)^2\left(\pi 2 p_y\right)^2\left(\sigma 2 p_z\right)^2 \\ & \text{Bond order }=\frac{8-2}{2}=3 \end{aligned}$$\begin{gathered} \mathrm{O}_2^{-}: K K(\sigma 2 s)^2(\sigma 2 s)^2\left(\sigma 2 p_z\right)^2\left(\pi 2 p_x\right)^2 \\ \left(\pi 2 p_y\right)^2\left(\pi 2 p_x\right)^2\left(\pi 2 p_y\right)^1 \\ \text{Bond order }=\frac{8-5}{2}=1 \frac{1}{2} \end{gathered} $$\begin{aligned} & \mathrm{NO}: K K(\sigma 2 s)^2(\sigma 2 s)^2\left(\sigma 2 p_z\right)^2\left(\pi 2 p_x\right)^2 \\ & \left.\left(\pi 2 p_y\right)^2(\pi) p_x\right)^1 \end{aligned}$$$Bond order$=\frac{8-3}{2}=2 \frac{1}{2}$Hence, the order of increasing bond order is as:$\underset{\left(\frac{1}{2}\right)}{\mathrm{He}_2^{+}} < \underset{\left(1 \frac{1}{2}\right)}{\mathrm{O}_2^{-}} < \underset{\left(2 \frac{1}{2}\right)}{\mathrm{NO}} < $$\mathrm{C}_2^{2-}$