Question

MO configuration of $He_2^-$ is
(a) (σ 1s)², ($\sigma^*$ 1s)², (σ 2s)¹
(b) (σ 1s)², ($\sigma^*$ 1s)², ($\sigma^*$ 2s)¹
(c) (σ 1s)², ($\sigma^*$ 1s)¹, (σ 2s)²
(d) (σ 1s)², ($\sigma^*$ 1s)¹, ($\sigma^*$ 2s)²

Answer 1

the answer to this question is