Carbon monoxide is 1. an atom, an element and a mixture. 2. a molecule, element and a pure substance. 3. an atom, a compound and a mixture. 4. an atom, an element and a pure substance. 5. a molecule, a compound and a mixture. 6. a molecule, a compound and a pure substance.

The correct answer is option (6).

Explanation:

A molecule is group of atoms of same or different kinds of element.

In carbon monoxide there is a single carbon atom and single oxygen atom. Hence, a molecule.

Compound is defined as a chemical specie which is made by the combination of different atoms.

As we can see from the chemical formula of carbon monoxide is made up of two atom of different elements that is carbon and oxygen.

A pure substance is defined as the substance which is formed by same or different type of atoms which are chemically combined in a fixed ratio by mass. They have definite set of properties.

1 mole of carbon combined with 0.5 moles of oxygen gas to give carbon monoxide gas.