Camphor
Explanation
Sublimation is the physical process in which a substance transitions directly from the solid phase to the gaseous phase without passing through the intermediate liquid phase. This phenomenon occurs in substances where the intermolecular forces are relatively weak, allowing molecules to escape the solid lattice directly into vapor upon heating.
Option Analysis
- Sodium Chloride is incorrect: Sodium Chloride (NaCl) is an ionic solid with strong electrostatic forces of attraction between ions. It has a high melting point ($801^\circ\text{C}$) and melts into a liquid state before vaporizing at much higher temperatures.
- Potassium Permanganate is incorrect: Potassium Permanganate ($KMnO_4$) is an ionic crystalline solid. Upon heating, it typically decomposes to release oxygen rather than undergoing sublimation.
- Camphor is correct: Camphor is a volatile organic solid characterized by weak Van der Waals forces between its molecules. Upon heating, it bypasses the liquid state and converts directly into vapor. This property is commonly utilized in purification processes.
- Sugar is incorrect: Sugar (Sucrose) melts into a liquid upon heating and subsequently undergoes decomposition (caramelization) rather than sublimation.
Key Takeaway
Sublimation is a characteristic property of specific solids such as Camphor, Naphthalene, Anthracene, Ammonium Chloride, Iodine, and Dry Ice (Solid $CO_2$). It is frequently used as a separation technique to purify volatile solids from non-volatile impurities.