The expression shown is V \(\propto\) nT/P. This can be derived from the ideal gas equation PV = nRT, which rearranges to V = nRT/P. Since R is a constant, V is directly proportional to nT/P.
This expression combines three individual gas laws into one:
Boyle's law: V \(\propto\) 1/P (at constant n and T)
Charles' law: V \(\propto\) T (at constant n and P)
Avogadro's law: V \(\propto\) n (at constant T and P)
Because the expression accounts for changes in all three variables (amount of substance n, temperature T, and pressure P) simultaneously, it represents the general gas law, not any single individual law.
