What is the correct form of the ideal gas law?

• A. PV = nRT
• B. P V = n R T^2
• C. P V = n R / T
• D. P V = n / (R T)

Answer: (A)

PV = nRT relates pressure, volume, temperature, and amount of gas for an ideal gas. It’s set up so both sides have the same physical units: with SI units, Pa·m^3 equals joules, and nRT = (moles) × (J/(mol·K)) × (K) also gives joules. This balance is what makes the equation consistent across conditions.

That means increasing temperature at fixed amount of gas and fixed volume raises pressure since P = nRT/V. Conversely, increasing volume at fixed n and T lowers pressure. The constant R isn’t a mystery number; it’s the proportionality factor that converts temperature and amount into the same energy units, and its numerical value depends on the units you use (for example, 8.314 J/(mol·K) in SI, or 0.082057 L·atm/(mol·K) when using liters and atmospheres).

The other forms would misalign the relationship with temperature or break unit consistency, so they don’t describe the behavior of an ideal gas correctly.