Question

How many oxygen atoms are present in 5.2 g of O2?

Answer 1

Since there are Avagadro Number of O2 atoms in 32g of O2, a simple cross multiplication gets you the answer.

\[6.022*10^ 23 ->32g \]
\[x->5.2g\]

\[x=\frac{6.022*10^23*5.2 }{ 32 }\]

Answer 2

Well that gives you the number of molecules. For atoms just multiply by 2.