Final answer:
The direct conversion of a gas into a solid without passing through the liquid state is called deposition, which is the reverse process of sublimation.
Step-by-step explanation:
If the sample in problem 3, which is a gas, was converted directly into a solid, the process that has taken place is called deposition. In this process, a gas undergoes a phase change directly into a solid state, bypassing the liquid phase entirely. Sublimation is the opposite process, where a solid changes directly into a gas. Examples of deposition include the formation of frost and the transformation of water vapor into ice without becoming liquid.
Deposition involves the molecules of a gas losing enough energy to come together and form a solid structure. No intermediate liquid phase occurs in this transition. In contrast, sublimation occurs when a solid gains enough energy to bypass the liquid state and enter directly into the gaseous state, such as with dry ice (solid CO2) at room temperature.