1
2.5
3.5
3
Answer is Right!
Answer is Wrong!
The correct answer is B. 2.5.
The bond order of a molecule is a measure of the strength of the covalent bonds between its atoms. It is calculated by taking the difference between the number of bonding electrons and the number of antibonding electrons, and dividing by two.
In the case of carbon monoxide, there are four bonding electrons (two from the carbon atom and two from the oxygen atom) and two antibonding electrons. Therefore, the bond order is $\frac{4-2}{2} = 2.5$.
Option A is incorrect because it does not take into account the antibonding electrons. Option C is incorrect because it overestimates the number of bonding electrons. Option D is incorrect because it underestimates the number of bonding electrons.