Principle of purification of organic compounds

The method chosen for purification depends on separating the desired compound from impurities using differences in physical properties such as:

• boiling point
• solubility
• volatility
• sublimation tendency
• chemical behavior

What factors matter?

To select the proper purification method, we must know:

• the nature of the organic compound (for example, whether it is volatile, solid, liquid, heat-sensitive, soluble, etc.)
• the nature/presence of impurity (for example, whether the impurity is non-volatile, soluble, insoluble, colored, etc.)

Examples

• Distillation is used when the compound is volatile and impurities have different boiling points.
• Crystallization is used when the compound and impurity differ in solubility.
• Sublimation is used if one component sublimes and the other does not.
• Chromatography depends on different adsorption/partition behavior of compound and impurities.

So purification is clearly based on both the compound’s nature and the impurity present.

Evaluation of options

• A: Incorrect — purification definitely depends on these factors.
• B: Incorrect — not only impurity, but also the compound’s nature matters.
• C: Correct — it depends on nature of compound and presence of impurity.
• D: Incorrect — impurity must also be considered.

Final answer

$\boxed{\text{C}}$