Is the 3 in a molecule a coefficient, subscript, or element 3h2o2

Asolution contains 225 g of sodium chloride, nacl, dissolved in enough water to make a 0.25 l of solution. what is the molarity of the solution? a. 3.88 m, b. 1.03 m, c. 1.5 m, d. 15.5 m

How many moles of al3+ ions are in 1.25 moles of al2o3

Ineed to find the answer of this question because i dont understand it