Question

Which of the following substances is not sublime?
A) Ammonium chloride
B) Dry ice
C) Sodium chloride
D) Iodine

Answer 1

We also remember that sublimation stands for the conversion of a solid to a gas without being converted to the liquid state. Sublimation is a type of phase transition, or a change in a state of matter, just like melting, freezing, and evaporation.

Complete step by step answer: Now we discuss the sublimation reaction which is a process that occurs when a substance is converted from its solid state to its gaseous state without ever going through the liquid state. In sublimation process, when energy is provided to sublime solids and they readily convert to their gaseous states. Let’s discuss through options:

When heating ammonium chloride which forms a product such as $N{H_3}$ and $HCl$ by dissociation process. Ammonia and hydrogen chloride gases are produced by heating the ammonium chloride. Therefore, the option A is incorrect.

Dry ice (solid carbon dioxide) is an example of a solid that undergoes sublimation. Dry ice is special because as it transitions from a solid to a gas, it does not pass through a liquid phase directly changing to carbon dioxide gas. So dry ice undergoes sublimation. Therefore, the option B is incorrect.

Sodium chloride is an ionic solid and has high melting and boiling points. Therefore, it cannot change in the vapor phase simply at atmospheric pressure so it cannot sublimate. Therefore the option C is correct.

Iodine provides an excellent example of sublimation. Visible purple gas is formed when iodine sublimation. When solid iodine crystals are heated the iodine changes from a solid directly to a gas without passing through a liquid phase. Hence iodine undergoes sublimation. Therefore, the option D is incorrect.
Therefore, the correct answer is option C.

Note: Typically, solids undergo sublimation at low pressures (under vacuum).Because of having high boiling and melting point nature of iodine, carbon dioxide, naphthalene arsenic etc.. which undergo sublimation at standard atmospheric pressure.