JEE Main levelSingle correct optionDifficulty 2 of 3cb043
Which statement about canonical (resonance) structures is correct?
AAll canonical forms must have exactly the same energy
BThey are in rapid equilibrium with each other
CEach canonical form can be isolated under suitable conditions
DThey differ only in the arrangement of electrons, not of nuclei
Answer: D
Canonical forms are drawn on paper; only the hybrid exists, so there is no equilibrium and no isolation. Contributors need not have equal energy (only equivalent ones do). The atom positions must be fixed and only electrons shift.