The question asks to identify which substance among the given options undergoes sublimation. Sublimation is the process where a substance transitions directly from the solid to the gas state, without passing through the liquid state.

Sublimation: Solid to Gas Transition

Let's analyze the properties of each option:

• Nitrogen: Nitrogen is a gas at standard temperature and pressure. It does not typically undergo sublimation.
• Iodine: Iodine is a solid at room temperature. When heated, solid iodine transitions directly into iodine vapor (gas) and then back to solid upon cooling, exhibiting sublimation.
• Sucrose: Sucrose (common sugar) melts when heated, and at higher temperatures, it decomposes rather than sublimating.
• Calcium: Calcium is a metal. It has a high melting point and boils at a very high temperature; it does not readily sublime under normal conditions.

Identifying the Sublimating Substance

Based on the analysis, Iodine is the substance that exhibits sublimation among the choices provided.