Question

Which of the following pairs can be distinguished by Lucas test?

• A. Ethanol and ethylene glycol
• B. o- and p-cresol
• C. propan-1-ol and ethanol
• D. Butan-1-ol and 2-methylpropan-2-ol

Hint:

Lucas Test speed: $3^\circ$ (Immediate) > $2^\circ$ (5-10 mins) > $1^\circ$ (No reaction at RT).

Answer 1

The Correct Option is D

Step 1: Concept
The Lucas test (conc. $HCl + ZnCl_2$) distinguishes between $1^\circ$, $2^\circ$, and $3^\circ$ alcohols based on the rate of turbidity formation.
Step 2: Analysis

• Butan-1-ol: $1^\circ$ alcohol; no turbidity at room temperature.
• 2-methylpropan-2-ol: $3^\circ$ alcohol; forms turbidity immediately.

Step 3: Application
Because one reacts immediately and the other does not react at room temperature, they can be easily distinguished.
Step 4: Conclusion
Pair (D) is the correct choice.
Final Answer:(D)