10. What is the percentage composition of oxygen in \( \mathrm{H}_{2} \mathrm{O} \) ? (Molar mass of \( \mathrm{H}_{2} \mathrm{O}=18 \mathrm{~g} / \mathrm{mol} ; \mathrm{O}=16 \mathrm{~g} / \mathrm{mol} \) )

10. What is the percentage composition of oxygen in \( \mathrm{H}_{2} \mathrm{O} \) ? (Molar mass of \( \mathrm{H}_{2} \mathrm{O}=18 \mathrm{~g} / \mathrm{mol} ; \mathrm{O}=16 \mathrm{~g} / \mathrm{mol} \) )

Given 11.9 g Al what is the amount of Al in moles?

Determine the amount of moles in 12.15 g Mg .

How many mols are there in each of the following samples? (convert grams to mols) a. 42 grams of the radioactive isotope Carbon-14

\( K ( SO _ { 3 } ) + HCl - SO _ { 2 } KCl + H _ { 2 } O \)