Question

Definition of homo atomic molecules and hetro atomic

Answer 1

Hetro atomic molecules must have more than one type of atom, such as water (H2O). 
A homoatomic molecule is a molecule consisting of atoms of the same element. examples are - oxygen (O2), hydrogen (H2), and nitrogen (N2). Homo atomic molecules are also called "Diatomic" molecules.

Answer 2

The homo-atomic are the molecules with same types of atoms.
 Example: Hydrozen, surphur.
The hetero-atomic molecules are the molecules with different kinds of atoms. Example: water.