Which statement best describes the mass of a gas according to the ideal gas law?

• A. A gas has mass, which can be calculated using its molar mass and the number of moles.
• B. Gases do not have mass because they are not solid or liquid.
• C. Only noble gases have mass; other gases do not.
• D. The ideal gas law assumes gases have no mass.

Answer: (A)

Verified step by step guidance

1. Recall the ideal gas law 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.
2. Understand that the ideal gas law relates the amount of gas in moles (\(n\)) to measurable properties like pressure, volume, and temperature, but it does not directly mention mass.
3. Recognize that the mass of a gas can be found by multiplying the number of moles (\(n\)) by the molar mass (\(M\)) of the gas: \(m = n \times M\).
4. Note that gases do have mass, regardless of their physical state, and this mass is related to the amount of substance (moles) and the molar mass.
5. Conclude that the ideal gas law assumes gases behave ideally but does not assume gases have no mass; instead, mass can be calculated from the number of moles and molar mass.