Which one of the following molecules attains greater stability on formation of its diatomic monovalent anion?

Step-by-step solution

The stability of a molecule upon the formation of its diatomic monovalent anion depends on the change in bond order. The bond order is calculated as 1 2 (N_b - N_a) , where N_b is the number of bonding electrons and N_a is the number of antibonding electrons. For C ₂ , the configuration is _ 1s ² _ 1s ^ *2 _ 2s ² _ 2s ^ *2 _ 2p_x ² _ 2p_y ² . Bond order = 1 2 (8 - 4) = 2 . Adding an electron gives C ₂⁻ , configuration _ 1s ² _ 1s ^ *2 _ 2s ² _ 2s ^ *2 _ 2p_x ² _ 2p_y ² _ 2p_z ¹ . Bond order = 1 2 (9 - 4) = 2.5 . Si