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Identify the INCORRECT statement about real gases:

1. At Boyle's temperature, a real gas behaves like an ideal gas regardless of the applied pressure.
2. At the critical point, the compressibility factor Z equals 3/8.
3. If the temperature is increased four times at constant volume, the collision frequency Z1 becomes twice its original value.
4. At very high pressures, van der Waals constant b has a dominant effect over constant a.

Correct answer: At Boyle's temperature, a real gas behaves like an ideal gas regardless of the applied pressure.

Solution

At Boyle's temperature a real gas obeys Boyle's law (PV = const) only at low to moderate pressures; at very high pressures higher-order virial terms cause deviations, so the statement 'irrespective of pressure' is incorrect.

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