PV = nRT is the expression of which gas law?

• A. Boyle's Law
• B. Dalton's Law
• C. Ideal Gas Law
• D. Charles' Law

Answer: (C)

PV = nRT is the expression of the Ideal Gas Law. It shows that for an ideal gas, pressure times volume is proportional to the amount of substance (in moles) and the temperature, with a universal constant R linking them. This single relation captures how P, V, n, and T influence each other: for fixed n and T, PV is constant; for fixed P and n, V is proportional to T; and for fixed P and T, V is proportional to n. Historically, Boyle’s and Charles’ laws describe parts of this behavior under certain fixed conditions, and Avogadro’s idea about volume and amount is encompassed here as well. Real gases follow this relation closely only under certain conditions (usually high temperature and low pressure), which is why it serves as a foundational model.