CaO is heterogenous homogenous or a pure substance

CaO is a pure substance

Explanation:

Pure Substance:

Pure substances are those having same type of atoms or molecules.

for example a glass of water have all same kind of H₂O molecules.

Mixture:

Mixture is combination of one or more substances mix together.

for example a solution of water and salt have two types of molecules that is H₂O and NaCl, that are mix together and give a mixture

There are two types of mixture upon its physical appearance

Homogeneous Mixture:

Homogeneous mixtures are those which are not distinguish by naked eye but can be separated into its components by physical means.

examples are solution of water and salt and water ans sugar. as these both have two kids of substances mix together but can be separated.

Heterogeneous mixture:

Heterogeneous mixture are those which can be distinguishing by naked eye and can be separated into its components by physical means.

for example mixture of water and sand, mixture of sand and salt both mixture have two kinds of substances mixed together and the difference of two substances can be seen by naked eye.

Now

if we want to know that whether CaO is heterogeneous, homogeneous or a pure substance according to above explanation then it is a pure substance.

As CaO is one molecule and not two different substances, so it is a pure substance.