A solid substance has been given a specific amount of energy to directly change its phase to gas state. This process is termed as:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → Sublimation
Sublimation is the change of a solid directly into a gas on heating, without first becoming a liquid. Camphor, naphthalene balls, iodine, ammonium chloride and dry ice (solid carbon dioxide) sublime.
Why the other options are incorrect
Option (1) Evaporation — Incorrect. It is a liquid changing into vapour at its surface, below its boiling point.
Option (2) Transpiration — Incorrect. It is the loss of water vapour from plants, mostly through the stomata of the leaves.
Option (3) Condensation — Incorrect. It is the reverse of evaporation: a gas or vapour changing into a liquid on cooling.