Which equation represents the Combined Gas Law?

The Combined Gas Law succinctly relates pressure, volume, and temperature of a gas in one single formula, demonstrating how changes in one of these variables affect the others, given that the quantity of gas remains constant. The correct equation incorporates all three variables—pressure (P), volume (V), and temperature (T)—and allows for the comparison of initial conditions to final conditions.

In the correct choice, both sides of the equation reflect the relationship under constant moles of gas; hence, it’s structured as (P1)(V1)/T1 = (P2)(V2)/T2. This representation shows that the ratio of the products of pressure and volume divided by temperature remains constant when a gas is subject to changing conditions: from state 1 to state 2. This law is particularly useful because it combines several simple gas laws: Boyle's Law, Charles's Law, and Gay-Lussac's Law, effectively summarizing their relationships into one equation.

The other available choices do not accurately encompass the Combined Gas Law. Some present relationships specific to pressure and temperature or pressure and volume, but they do not integrate all three variables together in the context of varying conditions. Therefore, they do not effectively represent the principles of gas behavior as