Which among the given molecules can exhibit tautomerism ?

Which among the given molecules can exhibit tautomerism ?

1. $\mathrm{III}$ only.
2. Both $\mathrm{I} \mathrm{and} \mathrm{III}$.
3. Both $\mathrm{I} \mathrm{and} \mathrm{II}$.
4. Both $\mathrm{II} \mathrm{and} \mathrm{III}$.

Solution

Bridge-head carbon cannot be planar $\left({\mathrm{sp}}^2\right)$. Therefore, tautomerism will be shown only by and the enolic form would be .

Asked in: NEET 2016 (Phase 2)

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