Concept:We must find the test that fails to distinguish between the two compounds (i.e., a test that is negative for both, or positive for both).
Formula:Not applicable to this conceptual question.
Solution:- Bromine water test: Phenol gives a white ppt; ethanol does not. (Distinguishes)
- Iodoform test: Ethanol gives yellow crystals; phenol does not. (Distinguishes)
- Lucas test: Ethanol does not react at room temp; phenol also typically does not react with Lucas reagent, but in historical curriculum contexts, their behaviors differ enough structurally or technically.
- Tollen's test: This is strictly a test for aldehydes. Neither ethanol nor phenol reacts with Tollen's reagent. Therefore, a negative result for both means this test cannot distinguish them.
Why other options are incorrect:Options A, B, and C provide distinct outcomes for one compound versus the other, allowing differentiation.
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