Air is a _______A. Pure compound.B. Mixture of only compounds.C. Mixture of only elements.D. Mixture of both elements and compounds.

The smallest particles of a mixture are atoms/molecules of two or more elements/compounds. For example, the main constituent molecules of the mixture NAMELY, air are N2, O2, Ar, H2O, CO2. Hence, it is a mixture of both elements and compounds.The matter is classified into THREE types ‘element’, ‘compound’, and ‘mixture’.All the smallest particles (atoms/ molecules) in an element or a compound are alike, however, the smallest particles in a mixture are of two or more types.Difference between Element, Compound, and Mixture:ElementCompoundMixtureThe constituent substance of element is only one, and it is that element ITSELFTHE constituent substance of the compound is only one and it isthat compound itselfConstituent substances of the mixture are two or moreelements and/or compoundsAtoms/molecules of different elements are differentThe PROPORTION of constituentelements in a compound areconstant.The proportion of constituentsubstances in a mixture canchange.