OHST Practice Exam

Which law expresses the relationship between volume and pressure of gases at constant temperature?

1. Charles Law

2. Boyle's Law

3. Ideal Gas Law

4. Gas Constant Law

The correct answer is: Boyle's Law

The correct choice outlines Boyle's Law, which precisely describes the inverse relationship between the volume of a gas and its pressure when the temperature is held constant. According to this law, as the volume of a gas decreases, its pressure increases, provided that the temperature does not change. This relationship is mathematically represented as \( P \propto \frac{1}{V} \) or \( PV = k \), where \( P \) represents pressure, \( V \) represents volume, and \( k \) is a constant for a given amount of gas at a fixed temperature. Other laws mentioned in the options serve different purposes. Charles's Law deals with the relationship between volume and temperature, stating that volume increases with an increase in temperature when pressure is constant. The Ideal Gas Law combines Boyle's Law, Charles's Law, and Avogadro's principle to relate pressure, volume, temperature, and the number of moles of an ideal gas. The Gas Constant Law is not a standard term used in thermodynamics and does not apply to this question. Understanding these distinctions helps clarify why Boyle's Law is specifically applicable in this context.