JEE Main · 2009 · 12 Apr 2009 · Offline · Chemical Bonding and Molecular Structure

Using MO theory predict which of the following species has the shortest bond length ?

(A) $O_{2}^{2 +}$ ✓ Correct
(B) $O_{2}^{+}$
(C) $O_{2}^{-}$
(D) $O_{2}^{2 -}$

Answer: (A)

Solution

Bond length shortens as bond order rises, so the species of highest bond order has the shortest bond. Counting bonding minus antibonding electrons and halving gives bond orders of 3 for

O_{2}^{2 +}

, 2.5 for

O_{2}^{+}

, 1.5 for

O_{2}^{-}

and 1 for

O_{2}^{2 -}

. The largest of these belongs to

O_{2}^{2 +}

, which therefore has the shortest bond.

JEE Main · 2009 · 12 Apr 2009 · Offline · Single correct option

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