Under which conditions does the molar volume of a gas decrease?

For a gas, molar volume is proportional to temperature divided by pressure: Vₘ ∝ T/P. Comparing each condition with 273 K and 1.0 atm, choice A gives 273/2.0, or half the reference molar volume. The other choices give 1.5, 1, and 2 times the reference volume, respectively, so the molar volume is smallest at 273 K and 2.0 atm.

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