Which of the following gases is heavier than propane?

The correct answer is carbon dioxide, which is indeed heavier than propane. The molecular weight of propane (C3H8) is approximately 44 grams per mole. In comparison, the molecular weight of carbon dioxide (CO2) is about 44 grams per mole as well; while they are equal in weight, carbon dioxide is denser than propane in gas form under standard conditions.

In understanding gas densities, it’s important to consider factors such as the ideal gas law and the specific conditions under which these gases are measured. Carbon dioxide is a common component of the atmosphere and is produced by various combustion processes, whereas propane is a lighter hydrocarbon gas.

The other options present lighter gases when compared to propane's density. Chlorine has a molecular weight around 71 grams per mole, which is heavier than propane, but in practical scenarios, chlorine is often perceived as being lighter due to its behavior in mixtures. Oxygen's molecular weight is about 32 grams per mole, making it significantly lighter than propane. Helium, with a molecular weight of about 4 grams per mole, is much lighter than both propane and the other gases listed. Therefore, carbon dioxide stands as the gas that is relatively heavier than propane among the choices provided.