Which of the following species has highest bond energy?

\(\mathrm{O}_{2}^{2-}=K K^{\prime} \sigma 2 s^{2}, \sigma^{*} 2 s^{2}, \sigma 2 p_{z}^{2}, \pi 2 p_{x}^{2}, \pi 2 p_{y}^{2}\)
\(\pi^{*} 2 p_{x}^{2}, \pi 2 p_{y}^{2}\)
Bond order \(=\frac{N_{b}-N_{a}}{2}=\frac{8-6}{2}=1\)
(b) \(\mathrm{O}_{2}^{+}=K K^{\prime} \sigma 2 s^{2}, \sigma^{*} 2 s^{2}, \sigma 2 p_{z}^{2}, \pi 2 p_{x}^{2}=\pi 2 p_{y}^{2}\)
\(\pi^{\star} 2 p_{x}^{1}\)
Bond order \(=\frac{8-3}{2}=2.5\)
(c) \(\mathrm{O}_{2}^{-}=K K^{\prime} \sigma 2 s^{2}, \sigma^{\star} 2 s^{2}, \sigma 2 p_{z}^{2}, \pi 2 p_{x}^{2} \approx \pi 2 p_{y}^{2}\)
\(\pi 2 p_{x}^{2} \approx \pi \cdot 2 p_{y}^{*}\)
Bond order \(=\frac{8-5}{2}=1.5\)
(d) \(\mathrm{O}_{2}=K K^{\prime} \sigma 2 s^{2}, \sigma^{\star} 2 s^{2}, \sigma 2 p_{z}^{2}, \pi 2 p_{x}^{2} \approx \pi 2 p_{y}^{2}\)
\(\pi 2 p_{x}^{*} \approx \pi 2 p_{y}^{1}\)
Bond order \(=\frac{8-4}{2}=2\)
: Bond energy \(\propto \frac{1}{\text { Bond order }}\)
\(\therefore \mathrm{O}_{2}^{2-}\) has highest bond energy.