Which of the following species has resonance structures?

• A. O3 (ozone)
• B. NH3 (ammonia)
• C. CH4 (methane)
• D. CO2 (carbon dioxide)

Answer: (A)

Verified step by step guidance

1. Understand that resonance structures occur when a molecule can be represented by two or more valid Lewis structures that differ only in the placement of electrons, not atoms.
2. Examine each species' Lewis structure to determine if multiple valid electron arrangements exist:
3. For NH3 (ammonia), draw the Lewis structure with nitrogen bonded to three hydrogens and a lone pair; no alternative electron placements create valid resonance forms.
4. For CH4 (methane), carbon is bonded to four hydrogens with no lone pairs or multiple bonds, so no resonance is possible.
5. For CO2 (carbon dioxide), the Lewis structure has double bonds between carbon and each oxygen; although there are multiple bonds, the structure is symmetrical and does not have alternative resonance forms that differ in electron placement.
6. For O3 (ozone), draw the Lewis structure showing one double bond and one single bond between the oxygen atoms, with formal charges; the double bond can be placed between different oxygen atoms, creating resonance structures.