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
[tex]1.2\cdot10^{21}\frac{1mol}{6.022\cdot10^{23}}=1.99\cdot10^{-3}mol[/tex]Then, using that the molar mass of magnesium hydroxide is 58 g/mol we can calculate the grams
[tex]1.99\cdot10^{-3}mol\cdot58\frac{g}{mol}=0.115g[/tex]Finally, 1.2x10^21 formula units of magnesium hydroxide are 0.115 grams
ANSWER:
0.115
