Question

Which of the following is not a mixture?
A.Air
B.Sea water
C.Ice
D.Soil

Answer 1

Hint: Mixture must have more than one component irrespective of quantity, quality and state of the components. The pure compounds made up of different atoms are not considered as a mixture.

Complete step by step solution:
When two or more than two substances mix in a medium, then it forms a mixture. Medium can be solid, liquid or gas. The mixing substances or components can be in any proportion, mixture can be either homogeneous or heterogeneous. The properties of the mixture depend upon the individual component. Any state of matter can combine to form a mixture.
Air is a mixture of different types of gases like Nitrogen, oxygen, carbon dioxide. Smoke and dust particles too are present in the air. Their percentage or contribution in mixture varies place to place. Air is a heterogeneous mixture.
Sea water is a mixture of water and many salts. These salts vary greatly in physical and chemical properties with each other. Sea water too is a heterogeneous mixture.
Ice is not a mixture. It is pure water. Water exists in solid, liquid and gas form too. Solid state of water is ice. There are no other chemicals present in ice. Hence it is a pure substance.
Soil is a mixture of various salts, ions, molecules, elements and compounds. These components are not in definite proportions. Soil is a form of heterogeneous mixture.

Thus, the correct option is C.

Note: In a mixture, combining entities can mix in any proportion and/or state. But in compounds like carbon dioxide, Sodium chloride, nitric acid and etc, combining atoms/molecules come together in definite proportion. For example water or \[{{\text{H}}_2}{\text{O}}\] , irrespective of source of water; in water hydrogen and oxygen will always combine in the ratio of 2:1. Similarly compounds like \[{\text{C}}{{\text{O}}_2}\] always have carbon and oxygen in the ratio of 1:2, irrespective of from which method it is obtained.