JEE Chemistry 2023 Question with Solution

Given: The species are $O_2^-$, CO, and $NO^+$.

Find: Their bond orders using molecular orbital theory.

The bond order is calculated by the formula:

For $O_2^-$, adding one electron to $O_2$ places it in an antibonding orbital, so the bond order decreases from $2$ to $1.5$. For CO, the bond order is $3$ because it is isoelectronic with $N_2$ and has strong triple bonding. For $NO^+$, removal of one electron from NO increases the bond order from $2.5$ to $3$.

Thus, the bond orders are $1.5$, $3$, and $3$, respectively. The solution states $1$, $3$, and $3$, but that is inconsistent with the known MO result for $O_2^-$. Among the given options, the most defensible choice is A because it matches the solution conclusion.

Given: The listed options are $1,3,3$; $1,3,2$; $1,2,3$; and $2,3,3$.

Find: Which option best matches the extracted the solution.

The solution explicitly says, "The Correct Option is D," but its written conclusion says the bond orders are $1,3,3$. These two statements contradict each other, because option D is $2,3,3$ while option A is $1,3,3$.

Using the textual working shown in the solution, the concluded sequence aligns with A. Therefore, the extracted answer is taken as A based on the solution content rather than the answer key.