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

For an ideal gas, molar volume is proportional to temperature divided by pressure: Vₘ = RT/P. Compared with 273 K and 1.0 atm, the molar volume decreases when the temperature-to-pressure ratio is smaller. At 273 K and 2.0 atm, that ratio is half as large, so choice A, 273 K and 2.0 atm, gives a decreased molar volume.

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