The conversion of naphthalene into naphthalene vapours is called

The process by which a substance transitions directly from a solid phase to a gas phase without passing through an intermediate liquid phase is called sublimation. Naphthalene is a classic example of a sublimable solid; it slowly disappears over time as it turns into naphthalene vapour at room temperature. Other common substances that undergo sublimation include dry ice (solid CO2), camphor, and iodine crystals.

• Distillation is a technique used to separate liquid mixtures based on differences in their boiling points.
• Crystallization is the process where a solid forms from a solution, melt, or gas, often used for purification.
• Decomposition refers to a chemical reaction where a compound breaks down into simpler substances.