Which of the following compounds does not have resonance?

• A. $O_3$
• B. ${\mathrm{NO}}_3-$
• C. ${\mathrm{CH}}_4$
• D. ${\mathrm{CO}}_2$

Answer: (C)

Verified step by step guidance

1. Step 1: Understand what resonance means in organic chemistry. Resonance occurs when a molecule can be represented by two or more valid Lewis structures (resonance forms) that differ only in the placement of electrons, typically involving delocalized pi electrons or lone pairs adjacent to pi bonds.
2. Step 2: Analyze each compound to determine if resonance is possible. Look for conjugated pi systems, lone pairs adjacent to double bonds, or charges that can be delocalized through pi bonds.
3. Step 3: For ozone (O\_3), recognize that it has a resonance structure because the double bond and single bond between oxygen atoms can shift, delocalizing electrons over the molecule.
4. Step 4: For nitrate ion (NO\_3\^-), identify that it has resonance because the negative charge and double bonds can be delocalized over the three oxygen atoms, creating multiple resonance forms.
5. Step 5: For methane (CH\_4), note that it has only single bonds (sigma bonds) and no pi bonds or lone pairs that can be delocalized, so it does not have resonance. For carbon dioxide (CO\_2), it has double bonds between carbon and oxygen, but no resonance because the structure is linear and the double bonds are localized.