Question

Choose the correct statement of the following.

• A. Conversion of solid into vapors without passing through the liquid state is called sublimation.
• B. Conversion of vapors into solid without passing through the liquid state is called vaporization.
• C. Conversion of vapors into solid without passing through the liquid state is called freezing.
• D. Conversion of solid into liquid is called sublimation.

Answer 1

The correct option is A

Conversion of solid into vapors without passing through the liquid state is called sublimation.

The explanation for the correct option:

Option (A): Conversion of solid into vapors without passing through the liquid state is called sublimation

1. Generally on increasing temperature, a Solid change its state into liquid.
2. But some solids have the property of changing their state directly into vapors from solid with acquiring the intermediate liquid state. This process is defined as Sublimation.
3. When some of the molecules absorb heat energy, they gain more energy than their neighbors, overcoming the force of attraction and escaping into the vapor phase. This is known as an endothermic reaction because it requires additional energy.
4. It can be used as a highly effective purifying technique This is a good method for separation and purification when a solid is contaminated with non-volatile contaminants.
5. Example: At room temperature and pressure, dry ice, which is solid carbon dioxide, quickly sublimates, similarly, naphthalene balls used in mothballs easily sublimate.
6. Hence, it is the correct option.

The explanation for incorrect options:

Option (B): Conversion of vapors into solid without passing through the liquid state is called vaporization.

1. A phase change from liquid to vapor is characterized as the vaporization.
2. As the temperature increases, the kinetic energy of the molecules increases. As kinetic energy rises, the force of attraction between molecules decreases. As a result, they are released into the atmosphere as vapors. This method requires the use of heat energy.
3. Example: The process of vaporization is used to extract salt from seawater and to help to dry wet garments.
4. Hence, it is an incorrect option.

Option (C): Conversion of vapors into solid without passing through the liquid state is called freezing

1. Solidification or freezing, is a phase transition in which a liquid becomes a solid when its temperature is decreased below its freezing point.
2. It is an exothermic reaction, meaning that heat is expelled as a result of the process.
3. Example: Snow, ice cubes.
4. Hence, it is an incorrect option.

Option (D): Conversion of solid into liquid is called sublimation

1. Melting, also known as fusion, is a physical process that causes a solid to become a liquid.
2. This happens when a solid's internal energy rises, usually due to the application of heat or pressure, raising the temperature to the melting point of the substance.
3. Example: melting of ice cubes, wax dripping from burning candles.
4. Hence, it is an incorrect option.

Therefore, the Conversion of solid into vapors without passing through the liquid state is called sublimation is the correct option.