To answer this question, we need to convert grams to moles and then use the Avogadro's number to convert moles to molecules.
The molar mass of Mg(OH)2 is 58.32 g/mol.
First, we need to find the number of moles of Mg(OH)2 in 75.0 g.
75.0 g / 58.32 g/mol = 1.287 mol
Next, we need to convert moles to molecules.
1.287 mol x 6.022 x 10^23 molecules/mol = 7.75 x 10^23 molecules
Finally, we can use the molecular formula of Mg(OH)2 to calculate the number of miles of Mg(OH)2.
1 molecule of Mg(OH)2 contains 3 atoms of oxygen (O) and 2 atoms of hydrogen (H).
So, the total number of miles of Mg(OH)2 is:
7.75 x 10^23 molecules x 2 miles/molecule = 1.55 x 10^24 miles
Therefore, there are 1.55 x 10^24 miles of magnesium hydroxide in 75.0 g of magnesium hydroxide.