Which of the following has least bond energy?

\(\begin{aligned} \mathrm{N}_{2}^{2-}=K K^{\prime} \sigma 2 s^{2}, \sigma 2 s^{2}, \sigma 2 p_{z}^{2}, \pi 2 p_{x}^{2}, \approx \pi & 2 p_{y}^{2} \\ & \pi 2 p_{x}^{2} \end{aligned}\)
\(\begin{aligned} \therefore \text { Bond order } &=\frac{N_{b}-N_{a}}{2} \\ &=\frac{8-4}{2}=2 \end{aligned}\)
(b) \(\mathrm{N}_{2}^{-}=K K^{\prime} \sigma 2 \mathrm{~s}^{2}, \sigma 2 \mathrm{~s}^{2}, \sigma 2 p_{z}^{2}, \pi 2 p_{x}^{2}=\pi 2 p_{y}^{2}\)
Bond order \(=\frac{8-3}{2}=2.5\)
(c) \(\mathrm{N}_{2}^{+}=K K^{\prime} \sigma 2 s^{2} \sigma 2 s^{2}, \pi 2 p_{x}^{2}=\pi 2 p_{y}^{2}, \sigma 2 p_{z}^{1}\)
Bond order \(=\frac{7-2}{2}=2.5\)
(d) \(\mathrm{N}_{2}=K K^{\prime} \sigma 2 s^{2}, \sigma^{\dagger} 2 s^{2}, \pi 2 p_{x}^{2}=\pi 2 p_{y}^{2}, \sigma 2 p_{z}^{2}\)
Bond order \(=\frac{8-2}{2}=3\)
\(\because\) Bond energy \(\propto \frac{1}{\text { Bond order }}\)
\(\therefore \mathrm{N}_{2}\) has least bond energy.