* Molar Mass: Chlorine (Cl₂) has a molar mass of approximately 70.9 g/mol, while oxygen (O₂) has a molar mass of approximately 32 g/mol. This means a single molecule of chlorine is heavier than a single molecule of oxygen.

* Density: Because chlorine is heavier, it will also have a higher density in its gaseous state, meaning a given volume of chlorine gas will weigh more than the same volume of oxygen gas.

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