Question

Sol. [Key Concept: MO theory — Ne₂ HOMO and zero bond order]

${Ne}_{2}:\sigma 1{\text{ }s}^{2} < \sigma^{*}1{\text{ }s}^{2} < \sigma 2{\text{ }s}^{2} < \sigma^{*}2{\text{ }s}^{2} < \sigma 2p_{z}^{2} < \left( \pi 2p_{x}^{2} = \pi 2p_{y}^{2} \right) < \pi^{*}2p_{x}^{2} = \pi^{*}2p_{y}^{2} < \sigma^{*}2p_{z}^{2}$ $\sigma^{*}2p_{z}$ i.e. $\sigma^{*}2p$ is highest occupied orbital.