On heating, some solid substances change from solid to vapour state without passing through liquid state. The technique used for the purification of such solid substances based on the above principle is known as

The correct option is Sublimation.

Let's break down the logic and definitions behind the purification techniques to understand why this is the correct answer:

1. Understanding the Principle:
When a solid substance is heated, it typically melts into a liquid first and then vaporizes into a gas upon further heating. However, some substances have a unique property where they bypass the liquid state entirely. The phase transition directly from solid to vapour (and vice-versa upon cooling) is called sublimation.

2. Application in Purification:
This behaviour is exploited to separate a sublimable solid compound from non-sublimable impurities. When the impure mixture is heated, the sublimable compound turns into vapour, leaving the non-volatile impurities behind in the heating vessel. The vapours of the pure substance are then condensed back into a solid on a cooled surface (a process sometimes referred to as deposition). Common examples of substances purified this way include camphor, naphthalene, ammonium chloride, benzoic acid, and iodine.

Let's evaluate the other options to see why they do not apply:
- Crystallization: This method is used to purify solid organic compounds based on their differential solubility in a solvent at room temperature versus higher temperatures.
- Distillation: This technique is used to separate volatile liquids from non-volatile impurities or to separate mixtures of liquids with different boiling points.
- Chromatography: This is a separation technique used to analyze, identify, and purify components of a mixture based on their differential partitioning between a stationary phase and a mobile phase.