Which of these represents the correct order of decreasing bond order?

Step-by-step solution

aligned & He ₂⁺: 1 s^2, 1 s^1 & BO = 1 2 (N_b-N_a )= 1 2 (2-1)= 1 2 =0.5 & C ₂²⁻: 1 s^2, ^* 1 s^2, 2 s^2, ^* 2 s^2, ( 2 p_x^2 2 p_y^2 ), 2 p_z^2 & BO = 1 2 (10-4)= 6 2 =3.0 & O ₂⁺= 1 s^2, ^* 1 s^2, 2 s^2, ^* 2 s^2 2 p_z^2 ( 2 p_x^2 2 p_y^2 ), & BO = 1 2 (10-5)= 5 2 =2.5 & O ₂⁻= 1 s^2, ^* 1 s^2, 2 s^2, ^* 2 s^2, 2 p_z^2 ( 2 p_x^2 2 p_y^2 ), & BO = 1 2 (10-7)= 3 2 =1.5 ( ^* 2 p_x^2 ^* 2 p_y^1 ) aligned Thus, the correct order of decreasing bond order is C ₂²⁻> O ₂⁺> O ₂⁻> He ₂⁺