The $\mathrm{Mo}-\mathrm{Mo}$ bond order in $\left[\left(\eta^{5}-\mathrm{C}_{5} \mathrm{H}_{5}\right) \mathrm{Mo}(\mathrm{CO})_{2}\right]_{2}$ which obeys the 18-electron rule is ____
Answer
Answer (as printed): 3
The options are missing from the source scan for this question, so there is nothing here for this letter to point at. The letter is what the book printed.