Question

Which of the following statements regarding melting point and freezing point of a substance is correct?
A.Melting point of a substance is more than its freezing point.
B.Melting point of a substance is less than its freezing point.
C.Melting point and freezing point of a substance are numerically the same.
D.None of the above.

Answer 1

Hint: Melting point: It is defined as the process of conversion of solid to liquid at atmospheric pressure.
Freezing point: It is defined as the process of conversion of liquid to solid at atmospheric pressure.

Complete step by step solution:
There are mainly three states of matter known as: solids, liquids and gases.
Solids: Solids are those states of matter which have definite shape and definite volume. Fixed shape means if we place them in any container then their shape will not change. It will be the same as before.
Liquids: Liquids are those states of matter whose atoms or particles are held together by intermolecular force which is less than that of forces in solids.
Gases: Gases are those states of matter whose atoms or particles are held together by a very weak force of attraction i.e. vanderwaal force of attraction which is less than that of forces in solids and in liquids. Gases do not have definite volume and do not have definite shape.
Evaporation: It is a process in which liquid is converted into vapours. The conversion of one state of matter to another can be explained on the basis of energy transfer between the molecules when they collide with each other. When we give heat to the system then they move faster and when they move fast in a system then they release heat and convert to another state.
The conversion of solid to liquid is known as melting, conversion of solid to gas without going into liquid phase is known as sublimation, conversion of liquid to solid is known as freezing or solidification, conversion of liquid to gas is known as vaporization, conversion of gas to solid without going to liquid phase is de-sublimation and conversion of gas to liquid is known as condensation.
Hence the conversion of solid to liquid is known as melting and the conversion of liquid to solid is known as freezing point. They both are numerically the same.

Hence, option C is correct.

Note: Sedimentation: It is defined as the process to remove suspended solid particles from using gravity, is known as sedimentation. For example: removal of sand or salt from water.
Decantation: It is defined as the process for the separation of mixture of immiscible liquids (which are not miscible), known as decantation.