Question

How many Liters of hydrogen gas are produced if 3.52 g of magnesium react with excess nitric acid at STP?

Answer 1

Mg + 2HNO3 = Mg(NO3)2 + H2
so, you get one mole of H2 for every mole of Mg
how many moles of Mg in 3.52g?
1 mole occupies 22.4L at STP, so ...