Question
Question: State true or false: “The process due to which a gas changes into a liquid at a fixed temperature is...
State true or false: “The process due to which a gas changes into a liquid at a fixed temperature is called vaporization.”
A. True
B. False
Solution
Hint
Gas, liquid, and solid are the three general states of matter. For a material these states are interchangeable depending on the physical conditions like the temperature and pressure of the surroundings.
Complete step by step answer
The matter around us is known to exist in three general states: gas, liquid and solid. Gas has no definite shape, and tends to take the form of the container it is put in. The molecules in a gas are very far apart and roam about in all the directions aimlessly. When these molecules are brought closer together by applying some pressure or decreasing the temperature, the state of matter turns to liquid from gas. Liquids also tend to take the shape of the container that they are put in, and they have a definite volume.
In solid state, the molecules are very closely packed. This causes the matter to have its own definite shape in the form of crystals and boundaries.
Condensation is the process of change of liquid from its gaseous form into liquid state. Condensation generally occurs in the atmosphere when warm air rises, and cools. This makes the air lose its capacity to hold water vapour. Consequently, this excess water vapour condenses to form cloud droplets.
On the other hand, vaporisation of a compound or element is the phase transition from liquid to gaseous state. Hence, to answer our question, the process due to which a gas changes into liquid is condensation and not vaporisation.
Thus, the given statement is False, and the correct option is (B).
Note
Evaporation and boiling are the types of vaporization. Evaporation is a surface phenomenon, while boiling is a bulk phenomenon. For example, the water in an open pond constantly evaporates from the surface due to the heat from the Sun, but while boiling water on the stove, all of the molecules in the volume get heated up simultaneously.