The highest molecular orbitals for an excited electronic configuration of the oxygen molecule are $\left[1 \pi_{g}\right]^{1}\left[3 \sigma_{u}\right]^{1}$. A possible molecular term symbol for oxygen with this electronic configuration is
(a)${ }^{1} \Pi$
(b)${ }^{3} \Sigma$
(c)${ }^{1} \Delta$
(d)${ }^{1} \Sigma$
Answer
Answer: A ✓ checked by 4AB · confidence high
Explanation
πg¹σu¹ gives Λ = 1, a Π state (singlet or triplet): ¹Π (a).