Which of the following molecules exhibits resonance?

• A. Nitrate ion (${\mathrm{NO}}_3-$)
• B. Benzene ($C_6{H}_6$)
• C. Ethane ($C_2{H}_6$)
• D. Methane (${\mathrm{CH}}_4$)

Answer: (B)

Verified step by step guidance

1. Identify the concept of resonance: Resonance occurs when a molecule can be represented by two or more valid Lewis structures (resonance structures) that differ only in the placement of electrons, not atoms.
2. Examine each molecule's structure to determine if resonance is possible by looking for conjugated pi bonds, lone pairs adjacent to pi bonds, or delocalized electrons.
3. For the nitrate ion (NO\_3\^-), recognize that it has three equivalent resonance structures where the double bond between nitrogen and oxygen shifts among the three oxygen atoms, indicating resonance.
4. For benzene (C\_6H\_6), understand that it has a cyclic, planar structure with alternating double bonds that are delocalized over the ring, which is a classic example of resonance.
5. For ethane (C\_2H\_6) and methane (CH\_4), note that these molecules have only single bonds with localized electrons and no possibility for resonance structures.