Answer: Element
Explanation:
Mixture is a substance which has two or more components which do not combine chemically and do not have any fixed ratio in which they are present. Example: Air
Compound is a pure substance which is made from atoms of different elements combined together in a fixed ratio by mass.It can be decomposed into simpler constituents using chemical reactions. Example: water [tex]H_2O[/tex]
Solution is a homogeneous mixture of a solute and a solvent. Example: salt in water
Element is a pure substance which is composed of atoms of similar elements. It can not be decomposed into simpler constituents using chemical reactions.Example: Gold [tex](Au)[/tex]
Thus pure gold is an element.
