How was avagadros number was calculated

i guess i have two questions....

1) the first is although I know the calculation of the number is based around the mass of 12 grams of carbon-12 and that there are 6.02*10^23 atoms here. How was it found that this many atoms of carbon was found in the 12 grams?

2) my second question is more based on his law which states "equal volumes of different gases at the same temperature and pressure contain the same number of particles."
referenced here

now my question here is that lets say we have a very small finite volume that can hold 10 hydrogen atoms, and assuming that the temperatures are equal and pressure is equal

how can the same volume hold the same number of atoms of radon which is much larger than hydrogen?

Mute
Homework Helper
i guess i have two questions....

1) the first is although I know the calculation of the number is based around the mass of 12 grams of carbon-12 and that there are 6.02*10^23 atoms here. How was it found that this many atoms of carbon was found in the 12 grams?

2) my second question is more based on his law which states "equal volumes of different gases at the same temperature and pressure contain the same number of particles."
referenced here