Which of the following statements is true for ideal gases?

• A. Ideal gases condense into liquids at low temperatures.
• B. Ideal gases experience strong intermolecular forces.
• C. The pressure of an ideal gas decreases as the number of moles increases at constant volume and temperature.
• D. The volume of an ideal gas is directly proportional to its temperature at constant pressure.

Answer: (D)

Verified step by step guidance

1. Recall the ideal gas law, which is given by the equation \(P \times V = n \times R \times T\), where \(P\) is pressure, \(V\) is volume, \(n\) is the number of moles, \(R\) is the gas constant, and \(T\) is temperature in Kelvin.
2. Understand that ideal gases are hypothetical gases that follow the ideal gas law perfectly and have no intermolecular forces and occupy no volume themselves.
3. Analyze each statement: - Ideal gases do not condense into liquids because they have no intermolecular forces. - Ideal gases do not experience strong intermolecular forces by definition. - According to the ideal gas law, at constant volume and temperature, pressure is directly proportional to the number of moles, so pressure increases, not decreases, as moles increase.
4. Focus on the relationship between volume and temperature at constant pressure and moles. From the ideal gas law, if \(P\) and \(n\) are constant, then \(V\) is directly proportional to \(T\), which means as temperature increases, volume increases proportionally.
5. Conclude that the true statement is: 'The volume of an ideal gas is directly proportional to its temperature at constant pressure,' which is a direct consequence of the ideal gas law.