Answer:
70.9 g/mol
Explanation:
To find the molar mass, you first need to convert molecules to moles via Avogadro's Number.
Avogadro's Number:
6.022 x 10²³ molecules = 1 mole
2.123 x 10²¹ molecules X₂ 1 mole
-------------------------------------- x ------------------------------------ = 0.00353 moles X₂
6.022 x 10²³ molecules
Now, you can plug the molar value and mass (given) into the molar mass ratio to find your final answer. Your answer should have 3 sig figs to reflect the given value with the lowest amount of sig figs (0.250 g).
Molar Mass (g/mol) = mass (g) / moles
Molar Mass = 0.250 g / 0.00353 moles
Molar Mass = 70.9 g/mol
