Question

What is $\text{O}-\text{O}$ bond length in resonance hybrid of ozone?

• A. 131 pm
• B. 121 pm
• C. 128 pm
• D. 148 pm

Hint:

For ozone ($\text{O}_3$), remember that its bond length (128 pm) lies perfectly intermediate between the regular $\text{O}-\text{O}$ single bond (148 pm) and the $\text{O}=\text{O}$ double bond in molecular oxygen (121 pm).

Answer 1

The Correct Option is C

Step 1: Picture ozone.
Ozone is a resonance hybrid. On paper one bond looks single and the other looks double, but the real molecule is a blend of the two.

Step 2: What blending does.
Because the electrons spread out evenly, both bonds become the same. Each has a bond order of about 1.5, so the length sits between a single bond near 148 pm and a double bond near 121 pm.

Step 3: The measured value.
Experiments give both bonds a length of 128 pm, right in the middle as expected.
\[ \boxed{128\ \text{pm},\ \text{option 3}} \]