• # question_answer Number of $\pi$ electrons in cyclobutadienyl anion ${{({{C}_{4}}{{H}_{4}})}^{-2}}$ is [IIT-JEE 1991] A) 2 B) 4 C) 6 D) 8

Cyclobutadienyl anion ${{({{C}_{4}}{{H}_{4}})}^{2-}}$