Explanation:
A compound is defined as the substance which contains different type of elements that chemically combine together in a fixed ratio by mass.
For example, [tex]CaCl_{2}[/tex] is a compound as it contains calcium and chlorine which are different elements. And, both Ca and Cl are combining in 1:2 ratio.
And, for every molecule of calcium chloride these elements will always be present in 1:2 ratio.
Thus, we can conclude that when a substance was analyzed in a laboratory. It was composed of three elements in a fixed ratio. The substance is a compound.
