You're asking for the molar masses of these molecules, which is the mass of one mole of the substance. Here's the breakdown:

* Molecular Oxygen (O2):

* Oxygen's atomic mass is approximately 16 grams per mole.

* O2 has two oxygen atoms, so its molar mass is 16 g/mol * 2 = 32 grams per mole.

* Hydrogen (H2):

* Hydrogen's atomic mass is approximately 1 gram per mole.

* H2 has two hydrogen atoms, so its molar mass is 1 g/mol * 2 = 2 grams per mole.

* Nitrogen (N2):

* Nitrogen's atomic mass is approximately 14 grams per mole.

* N2 has two nitrogen atoms, so its molar mass is 14 g/mol * 2 = 28 grams per mole.