Question

When a substance undergoes a phase change directly from the gas to the solid phase without the liquid phase in between, this is known as:

1) Sublimation
2) Condensation
3) Evaporation
4) Freezing

Answer 1

The process where a substance changes from a gas directly to a solid phase without passing through the liquid phase is known as deposition, which is the opposite of sublimation.

Step-by-step explanation:

When a substance changes from a gas directly to a solid phase without passing through the liquid phase, this process is referred to as deposition. This is the opposite of sublimation, which is the direct transition from a solid to a gas. The energy required during this phase change is measurable and combines the heat of fusion and the heat of vaporization.

Common examples of sublimation include dry ice transforming into CO₂ vapor, or solid iodine turning into purple gas upon being heated. Conversely, deposition occurs when frost forms from water vapor. These phase changes are physical processes governed by the addition or removal of heat at characteristic temperatures relevant to each substance.