Which of the following statements are correct? A. Glycerol is purified by vacuum distillation because it decomposes at its normal boiling point. B. Aniline can be purified by steam distillation as aniline is miscible in water. C. Ethanol can be separated from ethanol water mixture by azeotropic distillation because it forms azeotrope. D. An organic compound is pure, if mixed M.P. is remained same. Choose the most appropriate answer from the options given below :

We need to determine which statements about purification techniques are correct.

Statement A: "Glycerol is purified by vacuum distillation because it decomposes at its normal boiling point."

Glycerol has a normal boiling point of about 290 degC, but it begins to decompose around 250 degC. Vacuum distillation lowers the boiling point by reducing the pressure, allowing glycerol to be distilled at a lower temperature without decomposition. This statement is correct. ✓

Statement B: "Aniline can be purified by steam distillation as aniline is miscible in water."

While it is true that aniline can be purified by steam distillation, the reason given is incorrect. Steam distillation works for compounds that are immiscible (or sparingly soluble) in water, not miscible. Aniline is only slightly soluble in water (about 3.6 g/100 mL at 20 degC), which is why it can be steam-distilled - the two immiscible liquids distil at a temperature below the boiling point of either component. The statement incorrectly claims aniline is miscible in water. This statement is incorrect. ✗

Statement C: "Ethanol can be separated from ethanol-water mixture by azeotropic distillation because it forms an azeotrope."

Ethanol and water form a minimum boiling azeotrope at 95.6% ethanol (by weight) at 78.1 degC. Simple distillation cannot separate them beyond this composition. Azeotropic distillation (using a third component like benzene or cyclohexane as an entrainer) can break the azeotrope and separate pure ethanol. This statement is correct. ✓

Statement D: "An organic compound is pure, if mixed M.P. is remained same."

The mixed melting point test is a standard purity test: if a sample is mixed with a pure reference compound and the melting point remains unchanged (no depression), then the sample is the same pure compound. If impurities are present, the melting point would be depressed. This statement is correct. ✓

Conclusion: Statements A, C, and D are correct.

The correct answer is Option 2: A, C, D only.