Question

Which of the following have identical bond order? (I) $CN^-$ $\quad$ (II) $O_2 ^-$ $\quad$(III) $NO^+$ $\quad$ (IV) $CN^+$

• A. I, III
• B. I, II
• C. II, IV
• D. I, II, III

Answer 1

Answer: (A)

I, III

Answer 2

Isoelectronic species have same bond order. $CN^- = 6 + 7 + 1 = 14$ electrons, $O_2^ - = 8 + 8 + 1 = 17$ electrons, $NO^+ = 7 + 8 - 1 = 14$ electrons, $CN^+ = 6 + 7 - 1 = 12$ electrons.