A mixture of sand and naphthalene can be separated by

Correct answer: (a) sublimation

Explanation

Naphthalene is a volatile solid that undergoes sublimation, changing directly from solid to vapour on heating.

On heating the mixture, naphthalene vapour escapes and leaves behind the non-volatile sand.

Distillation and fractional distillation separate liquids, and chromatography separates dissolved components.