# Oxygen molecule is ______ times heavier than Helium molecule? (A) 2 (B) 4 (C) 8 (D) 16

Jul 25, 2017

Well, helium molecule , ${\text{He}}_{2}$, doesn't exist for any appreciable amount of time, but helium atom, $\text{He}$, does...

And helium atom has the atomic mass $\text{4.0026 g/mol}$, while oxygen molecule has the molecular mass $\text{31.998 g/mol}$.

Hence, oxygen molecule is about $8$ times as MASSIVE, and under the same gravitational field, is about $8$ times as heavy.

${\vec{F}}_{g} \left(H e\right) = {m}_{H e} \vec{g}$

${\vec{F}}_{g} \left({O}_{2}\right) = {m}_{{O}_{2}} \vec{g}$

$\implies \frac{{\vec{F}}_{g} \left({O}_{2}\right)}{{\vec{F}}_{g} \left(H e\right)} = {m}_{{O}_{2}} / \left({m}_{H e}\right) \approx 8$