QRC Chemist Evaluation Practice Exam 2026

The ideal gas law is expressed by the equation PV = nRT. In this equation, P represents the pressure of the gas, V is the volume, n denotes the number of moles of the gas, R is the universal gas constant, and T stands for the temperature measured in Kelvin. This equation describes the relationship among these four variables for an ideal gas, indicating how they interact in a closed system. It fundamentally captures the behavior of gases under various conditions and is foundational to the study of thermodynamics and physical chemistry. Other options present alternative relationships or forms that are not equivalent to the ideal gas law. For instance, one of them indicates that pressure is proportional to the volume and temperature divided by the amount of gas, which sets a different relationship among variables. Another option asserts that a ratio of pressure-volume to temperature is constant, which can apply under specific conditions but does not encompass the comprehensive relationships that the ideal gas law provides. Thus, A is the correct representation as it succinctly and accurately summarizes the interactions of pressure, volume, temperature, and amount of a gas in a single equation.