For a van der Waals gas, the constant a is larger for gases that:

Have weaker intermolecular attraction and resist liquefaction strongly

Simply have a smaller individual molecular size than other gases

Already behave nearly ideally at ordinary room temperature

For a van der Waals gas, the constant a…

Answer: Have stronger intermolecular attraction and are more easily liquefied.

A Have weaker intermolecular attraction and resist liquefaction strongly
B Have stronger intermolecular attraction and are more easily liquefied
C Simply have a smaller individual molecular size than other gases
D Already behave nearly ideally at ordinary room temperature

Correct answer: B. Have stronger intermolecular attraction and are more easily liquefied

Explanation: The constant a measures the strength of intermolecular attraction; gases with strong attractive forces (and hence higher critical temperatures) have larger a values.

Graph of pressure versus volume for a fixed amount of gas at constant temperature: the curve falls steeply then flattens, a hyperbola showing pressure inversely proportional to volume.

Boyle's law: at constant temperature the pressure of a fixed mass of gas is inversely proportional to its volume (P ∝ 1/V), so the P–V plot is a hyperbola — halving the volume doubles the pressure. Image: Reginaprice2013, CC BY-SA 3.0, via Wikimedia Commons.

Concept context

Discover why gases expand to fill any container while liquids flow and solids hold their shape. Master the gas laws, the ideal gas equation, and the reasons real gases deviate from ideal behavior.

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For a van der Waals gas, the constant a is larger for gases that:

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