What is the process by which a gas is converted into a solid?
- A. Deposition
- B. Sublimation
- C. Vaporisation
- D. Freezing
Answer: A. Deposition
The correct answer is A. Deposition.
- Deposition: This is the process where a gas directly changes into a solid state, bypassing the liquid phase. This often happens when the gas comes in contact with a cold surface, and the molecules lose enough kinetic energy to solidify without forming a liquid first. Examples include frost formation on windows and the growth of thin films in semiconductor manufacturing.
- Sublimation: This is the process where a solid directly changes into a gas state, again bypassing the liquid phase. This occurs when the solid’s vapor pressure exceeds the surrounding pressure, and the molecules directly escape into the gaseous state. Examples include dry ice sublimating and iodine crystals vaporizing.
- Vaporisation: This is the process where a liquid changes into a gas state. While it involves a phase change, it doesn’t directly convert a gas to a solid, so it’s not the correct answer.
- Freezing: This is the process where a liquid changes into a solid state. Again, it involves a phase change, but it starts from a liquid, not a gas, so it’s not the answer in this context.