Mass of 1 molecule of Nitrogen gas:
Nitrogen gas is define as N2. its moleculer mass will become 28.
For its one mole it is of 28gram.
According to mole concept in one mole there is 6.022*1023 moles are present.
So mass of 1 molecule of nitogen gas is 28/(6.022*1023) gram.
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Mass of 1 molecule of water(H2O):
Step #1 - the molar mass of water is 18.015 g/mol. This was calculated by multiplying the atomic weight of hydrogen (1.008) by two and adding the result to the weight for one oxygen (15.999).
Please remember that you need the molar mass first when trying to find the mass of one molecule.
Step #2 - divide the substance's molar mass by Avogadro's Number.
18.015 grams/mol ÷ 6.022 x 1023 mol-1 = 2.992 x 10-23 grams