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.