Several individual gas laws, Boyle's law linking pressure and volume, Charles's law linking volume and temperature, were each discovered independently through careful experiment before eventually being combined into the single ideal gas law now most familiar from physics. Chemistry's own use of that same underlying relationship took a genuinely different, and historically enormously important, direction: Avogadro's hypothesis, that equal volumes of gas under the same conditions of temperature and pressure contain equal numbers of molecules, let nineteenth-century chemists work out gas molecules' actual relative masses just from weighing measurable volumes of gas.
The individual gas laws were discovered separately, decades apart
Robert Boyle established the inverse relationship between a gas's pressure and volume at constant temperature in 1662, and Jacques Charles established the direct relationship between a gas's volume and temperature at constant pressure over a century later, in the 1780s. Each law was discovered through careful, separate experimental work well before anyone combined them into the single unified relationship physics now teaches as the ideal gas law, a genuine historical example of separate empirical discoveries only later being recognised as pieces of one bigger underlying picture.
Avogadro's hypothesis gave chemistry a way to actually weigh a molecule
In 1811, Amedeo Avogadro proposed that equal volumes of any gas, under identical temperature and pressure conditions, contain exactly the same number of molecules regardless of what gas it is. That hypothesis gave nineteenth-century chemists a genuinely new tool: by measuring the mass of a known volume of a gas under known conditions, they could work out that gas's molecules' relative mass compared with another gas's, which turned out to be foundational both to ordering the periodic table correctly and to settling the previously unclear distinction between atoms and molecules.
What we're still unsure about
That the individual gas laws were discovered separately before being unified, and that Avogadro's hypothesis let chemists determine gases' relative molecular masses, are well established, extensively documented facts of the history of chemistry. What's more genuinely a striking, well-documented historical fact is that it took roughly five decades after Avogadro's original 1811 proposal for the wider scientific community to actually accept the atom-versus-molecule distinction his hypothesis depended on, the idea only gained broad acceptance after Stanislao Cannizzaro forcefully argued for it at an 1860 chemistry conference, a genuine example of a logically sound idea sitting largely unrecognised for decades before the field caught up to it.
This sits inside Gas Laws, one of eight topics in General Chemistry, one of six domains in Chemistry, one of seventeen subjects the app can quiz you on.