Bond order of 1.5 is shown by

Step-by-step solution

aligned & (a) MO configuration of O ₂⁺(8+8-1=15) & = 1 s^2, ^* 1 s^2, 2 s^2, * 2 s^2, 2 p_z^2, & 2 p_x^2 2 p_y^2, 2 p_x^1 2 p_y^0 & BO = N_b-N_a 2 aligned (where, N_b= number of electrons in bonding molecular orbital N_a= number of electrons in anti-bonding molecular orbital BO = 10-5 2 =2.5 Similarly, (b) O ₂⁻(8+8+1=17) so BO = N_b-N_a 2 = 10-7 2 =1.5 (c) O ₂²⁻(8+8+2=18) BO = N_b-N_a 2 = 10-8 2 =1 (d) O ₂(8+8=16) BO = 10-6 2 =2 Thus, O ₂⁻ shows the bond order 1.5.