Question:

If the bond order of CO is \(x\), the bond order of \(O_2^{2-}\) ion is

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Using molecular orbital theory: \[ \text{Bond Order} = \frac{\text{Bonding electrons}-\text{Antibonding electrons}}{2} \] CO has bond order \(3\), while \(O_2^{2-}\) has bond order \(1\).
Updated On: Jul 18, 2026
  • \(x\)
  • \(x/2\)
  • \(x/3\)
  • \(2x\)
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The Correct Option is C

Solution and Explanation

Step 1: Calculate the bond order of CO.
Carbon monoxide is isoelectronic with \(N_2\). It contains \[ 14 \] electrons.
Using molecular orbital theory, \[ \text{Bond Order} =\frac{N_b-N_a}{2} \] For CO, \[ \text{Bond Order}=3 \] Hence, \[ x=3 \]

Step 2: Calculate the bond order of \(O_2^{2-}\).
Oxygen molecule has \[ 16 \] electrons. Therefore, \[ O_2^{2-} \] contains \[ 18 \] electrons.
Its molecular orbital configuration is similar to \(F_2\).
Number of bonding electrons: \[ N_b=10 \] Number of antibonding electrons: \[ N_a=6 \] Therefore, \[ \text{Bond Order} = \frac{10-6}{2} = 2 \] Wait, for \(O_2^{2-}\): \[ N_b=10,\qquad N_a=8 \] Thus, \[ \text{Bond Order} = \frac{10-8}{2} = 1 \]

Step 3: Express bond order in terms of \(x\).
Since \[ x=3 \] and \[ \text{Bond Order of }O_2^{2-}=1, \] we get \[ 1=\frac{3}{3} \] Therefore, \[ \text{Bond Order of }O_2^{2-} = \frac{x}{3} \]

Step 4: Verify the option.
The obtained expression matches option (3).

Step 5: Final conclusion.
Hence, \[ \boxed{\frac{x}{3}} \] is the correct answer.
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