Concept:Differentiation between two primary alcohols relies on specific structural tests. Ethanol contains a \(\text{CH}_3-\text{CH}(\text{OH})-\) terminal group, whereas methanol does not.
Formula:$$ \text{C}_2\text{H}_5\text{OH} \xrightarrow{\text{I}_2 / \text{NaOH}} \text{CHI}_3 \text{ (yellow ppt)} $$
Solution:- Methanol and ethanol are both primary alcohols, so they both give negative Lucas tests at room temperature.
- Ethanol reacts with Iodine and NaOH to give yellow crystals of Iodoform (\(\text{CHI}_3\)).
- Methanol yields no reaction under the same conditions.
Why other options are incorrect:Lucas test cannot distinguish them because neither reacts quickly. Silver mirror is for aldehydes. Oxidation gives formaldehyde vs acetaldehyde, which are harder to distinguish visually than a direct precipitation test.
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