Naphthalene balls disappear without leaving any solid. Give a reason.

Naphthalene balls, often used as mothballs, appear to disappear without leaving any solid residue due to a process called sublimation. Sublimation is the phase transition in which a substance changes directly from a solid to a gas without passing through the liquid phase.

Naphthalene has a relatively low melting point and vaporizes easily at room temperature. When you place naphthalene balls in a closed space, such as a closet or storage container, they slowly undergo sublimation. The naphthalene molecules on the surface of the balls absorb heat energy from their surroundings and transition from a solid state directly to a gaseous state. This transition happens over time, and as the naphthalene molecules evaporate into the air, the naphthalene balls gradually shrink in size until they seem to "disappear."

Since there is no liquid phase involved in this process, there is no solid residue left behind. Instead, the naphthalene molecules disperse into the air as a gas, and that's why naphthalene balls appear to vanish without leaving any solid remnants. It's important to note that the vapors released by naphthalene can be toxic in high concentrations, so they should be used in a well-ventilated area and kept out of the reach of children and pets.