Answer:
A compound
Explanation:
A compound is chemical entity that is formed when 2 or more elements are joined together in a fixed ratio.
This fixed ratio is simply the numerical values of the numbers of these elements. Take for example in the case of water, one atom of oxygen joins together with two atoms of hydrogen. The fixed ratio here is 1 to 2 or 2 to 1 depending on the reference element.
For example also in methane. The molecular formula of Methane is CH4. The ratio between carbon and hydrogen is 1 to 4 here
