Answer:
Explanation: A molecule of compound is formed by the combination of atoms of different elements combined together in a fixed ratio by mass.
Carbon dioxide is a covalent compound formed by sharing of electrons between carbon and two oxygen atoms in which less electronegative atom is named first followed by the more electronegative element with a prefix indicating the number of atoms followed by an -ide.
The number is represented by a stochiometric coefficient in the beginning of chemical formula.
Thus the correct representation of 3 molecules of carbon dioxide is