Here's why:
* Avogadro's Number: One mole of any substance contains the same number of particles (atoms or molecules), which is Avogadro's number (6.022 x 10²³).
* Different Molecular Weights: O₂ and NH₃ have different molecular weights. O₂ has a molecular weight of 32 g/mol, while NH₃ has a molecular weight of 17 g/mol.
Therefore, even though you have the same number of moles, you have a different number of molecules because the masses of the individual molecules are different.
