Air is made of of gaseous elements and compounds that interact but are not bound to each other. So air can be considered a Mixture.
A mixture is a combination of two or more substances that are not chemically combined, such that the substances in it are not bound to each other.
A mixture may be homogeneous or heterogeneous; in a homogeneous mixture all the components of the mixture are in the same phase while in a heterogeneous mixture the components are in different phase such as in the case of suspension.
Air is a mixture because the compounds that make up air such as nitrogen, oxygen, carbon dioxide, etc are not chemically combined, they are not bound to each other. It is a homogeneous mixture because or the substances in air are in a single phase, gaseous state.
