According to MO theory the bond orders for O _ 2 ^ 2 - , CO and NO...

(i) Molecular orbital configuration of ${O}_{2}^{2 -}$ is $KK ( \sigma2s{)}^{2} ( \sigma * 2s{)}^{2} 휋 ( 2{p}_{x}{)}^{2} 휋 ( 2{p}_{y}{)}^{2} ( \sigma2{p}_{z}{)}^{2} 휋 * ( 2{p}_{x}{)}^{2} 휋 * ( 2{p}_{y}{)}^{2}$

Bond order = $\dfrac{1}{2} ( {N}_{b} - {N}_{a} )=\dfrac{1}{2}\left(8 - 6\right) = 1$

(ii) Molecular orbital configuration of $CO$ is $KK ( \sigma2s{)}^{2} ( \sigma * 2s{)}^{2} 휋 ( 2{p}_{x}{)}^{2} 휋 ( 2{p}_{y}{)}^{2} ( \sigma2{p}_{z}{)}^{2}$

Bond order = $\dfrac{1}{2} ( {N}_{b} - {N}_{a} )=\dfrac{1}{2}\left(8 - 2\right) = 3$

(iii) Molecular orbital configuration of ${NO}^{+}$ is $KK ( \sigma2s{)}^{2} ( \sigma * 2s{)}^{2} 휋 ( 2{p}_{x}{)}^{2} 휋 ( 2{p}_{y}{)}^{2} ( \sigma2{p}_{z}{)}^{2}$

Bond order = $\dfrac{1}{2} ( {N}_{b} - {N}_{a} )=\dfrac{1}{2}\left(8 - 2\right) = 3$

So, according to molecular orbital theory, the bond orders respectively are 1, 3 and 3.