Question

Pure water is a ____ whereas pure air is a _________.

• A. compound
• B. mixture

Answer 1

• Pure water that contains only ${\mathrm{H}}_2\mathrm{O}$molecules is a compound.
• It is composed of two different elements i.e. hydrogen and oxygen that bond chemically in a fixed proportion.
• Thus, pure water is considered a compound.
• Air is a mixture of several gases like oxygen, nitrogen, carbon dioxide and other gases.
• The composition of air changes from place to place and from time to time. They retain their individual properties.
• Therefore, pure water is a compound whereas pure air is a mixture.