Question

A liquid can exist only:
(A) Between triple point and critical point
(B) At any temperature above melting point
(C) Between melting point and critical point
(D) Between boiling and melting points

Answer 1

A substance which flows or deforms continuously under stress or an external force is known as a fluid. Liquid is a type of fluid. The other two types of fluids are gases and plasmas. Liquids convert to gas above boiling point and into solid below melting point.

Complete Step by step solution:
The four fundamental states of matter are solid, gas, plasma and liquid. A liquid is a type of a fluid which changes its shape according to the shape of the container it is in, but does not change its volume whether there is an application of pressure or not. It is formed of tiny vibrating atoms, sustained together by the intermolecular bonds. The intermolecular forces of liquid are greater than that of gases but less than that of solids.
Triple point: The point of certain temperature and pressure at which solid, liquid and gaseous phases of a particular substance cohabit in equilibrium, is known as the triple point.
Critical point: The point of certain temperature, pressure and density at which the liquid and the gaseous phases of a particular substance becomes identical, is known as the critical point.
Melting point: The point of certain temperature at which a solid substance gets converted into a liquid substance, is known as the melting point.
Boiling point: The point of certain temperature at which a liquid substance gets converted into a gaseous substance, is known as the boiling point.
Hence a liquid can exist only between its boiling point and melting point as above the boiling point it will change into a gas and below the melting point it will change into a solid.
Therefore, the correct answer is option D.

Note:
Liquids exhibit unique properties of surface tension, which leads to the wetting phenomena. The tendency of a liquid surface to shrink into minimum surface area is known as surface tension.