The substance that would not be a compound is Cl3 (third option).
What is a compound?
A compound is a pure substance formed by chemical union of two or more ingredients in definite proportions by weight.
In a compound, two or more elements come together by chemical bond.
According to this question;
Glucose with the chemical formula C6H12O6, is a compound because it is made up of three elements
Sulfuric acid is also a compound because it is made up of hydrogen, sulfur and oxygen.
However, Cl3 is not a compound because it contains only chlorine atoms.
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