Avogadro's law implies that at fixed temperature and pressure a gas's volume depends on:

1. The law compares different gases under the same conditions. 2. Equal volumes of gaseous nitrogen, hydrogen and ammonia at the same temperature and pressure contain the same number of molecules. 3. So volume tracks molecule count and nothing about the molecules themselves. 4. Nitrogen and hydrogen molecules differ greatly in mass yet occupy the same volume. 5. That independence from molecular identity is what makes the law useful. _Source: OpenStax Chemistry 2e (CC BY 4.0), Ch 9 'Gases', sections 9.1-9.6_