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Avogadro’s law and gas density: proportionality with molecular mass For two gases at the same temperature and pressure, state how their densities compare with their molecular masses. Choose the correct relationship.

Difficulty: Easy

Directly proportional to molecular mass
Inversely proportional to molecular mass
Equal to molecular mass
Independent of molecular mass

Correct Answer: Directly proportional to molecular mass

Explanation:

ConceptAt the same T and p, Avogadro’s law implies equal molar volumes. Density ρ is ρ = (mass)/(volume) = (M molar mass)/(molar volume). With constant molar volume, ρ ∝ M.

Stepρ₁/ρ₂ = M₁/M₂

Final AnswerDirectly proportional to molecular mass

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