Separate the following into elements, mixtures and compounds. 

A-NaCl, B-Air, C-Water, D-HCl, E-Oxygen 

An element is composed of atoms that have the same atomic number, that is, each atom has the same number of protons in its nucleus as all other atoms of that element.

In chemistry, when two or more substances mix with each other without participating in a chemical change, the resulting substance is called a Mixture.

In chemistry, a compound is a substance made up of two or more different chemical elements combined in a fixed ratio. When the elements come together, they react with each other and form chemical bonds that are difficult to break.

Element-Oxygen 

Mixture-Mixture 

Compound-NaCl, Water, HCl