See image — Practical Organic Chemistry and Purification Chemistry Question

💡 Solution & Explanation

Concept: Methanol (CH3OH) is a simple aliphatic alcohol, while phenol (Ph-OH) is an aromatic alcohol with distinctly different chemical properties due to the resonance stabilization of the phenoxide ion. We need to identify which tests can distinguish between the two. Step 1 - Litmus test: Phenol is acidic enough (pKa ~10) to turn blue litmus red, because the phenoxide ion is stabilized by resonance with the aromatic ring. Methanol is essentially neutral and does not turn blue litmus red. Therefore, the litmus test can differentiate between methanol and phenol. Step 2 - FeCl3 test: Phenol gives a characteristic violet/purple colouration with FeCl3 solution due to formation of a complex [Fe(OPh)6]3-. Methanol does not give any colour with FeCl3. Therefore, FeCl3 test can differentiate between methanol and phenol. Step 3 - Br2/H2O (bromine water) test: Phenol undergoes electrophilic aromatic substitution readily; it reacts with bromine water to give a white precipitate of 2,4,6-tribromophenol and decolourises bromine water. Methanol does not react with bromine water under normal conditions. Therefore, Br2/H2O test can differentiate between methanol and phenol. Step 4 - Conclusion: All three tests — litmus test, FeCl3, and Br2/H2O — are individually capable of differentiating methanol from phenol. Hence, the answer is 'All of these'. Therefore, the correct answer is D.