How did physicists come to know that at a constant temperature and constant mass, the pressure of an ideal gas is inversely proportional to its volume?
(a) They could have conducted an experiment maintaining the gas as described above and made a pressure-versus volume graph.
(b) They could have derived this relationship using the equations describing the ideal gas model and the relationship between the speed of the particles and the gas temperature.
(c) Both a and b are correct.