How many moles of magnesium are needed to react with 16.0 g of O2?

2Mg + O2 - -> 2MgO

1.0 mol

0.50 mol

2.0 mol

4.0 mol

1 mol of Mg

Explanation:

2Mg + O₂ → 2MgO

2 moles of magnesium react with 1 mol of oxygen, to produce 2 mol of magnesium oxide.

16 g / 32 g/m = 0.5 moles of O₂

If 1 mol of oxygen react with 2 mol of Mg

0.5 moles of O₂ will react with 1 mol of Mg. (0.5 ₓ2)