Question

A vapour on cooling changes into ______ and on further cooling it changes to solid.
A.Gas
B.Liquid
C.Solid
D.None of these

Answer 1

Hint: We need to know and understand the different states of matter and how they can be changed from one form to another. Matter may exist in three different states: solid, liquid, or gas. Solid matter is made up of densely packed particles. A solid maintains its form; the particles are not free to move. Liquid matter is made up of particles that are more loosely packed. It will conform to the shape of its container. Gaseous stuff is made up of particles that are packed so loosely that it has no definite shape or volume.

Complete answer:
Phase transitions characterise a state of matter. A phase transition denotes a structural shift and may be identified by an abrupt change in characteristics. A distinct state of matter is any collection of states that can be differentiated from any other set of states by a phase transition. A particular set of matter's state or phase can vary based on pressure and temperature circumstances, transitioning to different phases when these variables alter to favour their existence; for example, solid changes to liquid as temperature rises. A material exists as a solid near absolute zero. When heat is applied to this material, it melts into a liquid at its melting point and then boils into a gas.
When a vapour is cooled, it condenses and becomes liquid. If we continue to cool the liquid, it will solidify at its freezing point. This is due to the fact that when the vapour cools, its kinetic energy drops but its intermolecular force of attraction rises.

Hence, the correct option is option (B).

Note:
Note that the phase transitions of matter from one form to another is important in a water cycle. The process through which water evaporates is known as evaporation. Water vapour is water in the form of a gas. Condensation is the formation of clouds from water vapour. Precipitation is the rain that falls when a cloud is fully formed.