Evaluating statements on separation techniques

Steps:

• Recall distillation separates liquids based on boiling point differences; a 35°C gap is sufficient for effective separation.
• For chromatography, locating agents visualize colorless spots, but ink dyes are colored and visible without them.
• Check Rf formula: it is distance spot travels divided by distance solvent travels, not the reverse.
• Option D lacks content, so it cannot be evaluated as correct.

Why A is correct:

• Simple distillation works for liquids with boiling point differences of at least 25–30°C, allowing one to vaporize and condense separately before the other boils.

Why the others are wrong:

• B: Colored inks show spots without locating agents; these are used only for invisible compounds.
• C: Rf formula is inverted; it equals spot distance divided by solvent distance for standardization.
• D: No statement provided, so invalid.

Final answer: A