In which one of the following molecules is the best Lewis structure represented as a resonance structure?

• A. H_2O (water)
• B. NH_3 (ammonia)
• C. O_3 (ozone)
• D. CH_4 (methane)

Answer: (C)

Verified step by step guidance

1. Understand what resonance structures are: Resonance structures are different Lewis structures for the same molecule that differ only in the placement of electrons (usually pi bonds or lone pairs), not in the arrangement of atoms.
2. Analyze each molecule's Lewis structure to see if multiple valid Lewis structures exist that differ only in electron placement:
3. For H_2O (water), NH_3 (ammonia), and CH_4 (methane), each has a single dominant Lewis structure with no alternative valid resonance forms because all bonds are single and lone pairs are fixed.
4. For O_3 (ozone), multiple Lewis structures can be drawn where the double bond and single bond positions between oxygen atoms can be switched, creating resonance forms that contribute to the actual structure.
5. Therefore, the best Lewis structure for O_3 is represented as a resonance hybrid of these multiple valid resonance structures.