We need to convert 1.2x10^21 formula units of magnesium hydroxide to grams
First, we must use that
Using that, we can calculate the number of moles of magnesium hydroxide
![1.2\cdot10^(21)(1mol)/(6.022\cdot10^(23))=1.99\cdot10^(-3)mol](https://img.qammunity.org/2023/formulas/chemistry/college/j40cnz4onhw0yvq91vjitpmrdnn9v1q3nx.png)
Then, using that the molar mass of magnesium hydroxide is 58 g/mol we can calculate the grams
![1.99\cdot10^(-3)mol\cdot58(g)/(mol)=0.115g](https://img.qammunity.org/2023/formulas/chemistry/college/n6zkr7oae9u5chvrjygbxpa9dfwu1pg77b.png)
Finally, 1.2x10^21 formula units of magnesium hydroxide are 0.115 grams
ANSWER:
0.115