Which one of the following substances is not a mixture ?
Tin
Sea water
Soil
Air
Answer is Right!
Answer is Wrong!
This question was previously asked in
UPSC NDA-2 – 2019
A) Tin (Sn) is a chemical element, found on the periodic table. Elements are pure substances, consisting only of one type of atom. Therefore, tin is not a mixture.
B) Sea water is a solution of various salts (like sodium chloride, magnesium chloride, etc.), dissolved gases, and other substances in water. It is a homogeneous mixture (a solution).
C) Soil is a complex combination of inorganic mineral particles, organic matter, water, air, and living organisms. It is a heterogeneous mixture.
D) Air is a mixture of gases, primarily nitrogen ($\text{N}_2$), oxygen ($\text{O}_2$), argon (Ar), carbon dioxide ($\text{CO}_2$), and trace gases. It is a homogeneous mixture (a solution of gases).
Since Tin is an element and not a combination of different substances physically mixed, it is not a mixture.
– Mixtures are physical combinations of two or more substances.
– Elements cannot be broken down into simpler substances by chemical means.