Three compounds used as fertilizers are urea, CO(NH 2 ) 2 ; ammonium nitrate, NH 4 NO

Question:

Three compounds used as fertilizers are urea, CO(NH₂)₂; ammonium nitrate, NH₄NO₃; and ammonium sulfate, (NH₄)₂SO₄. What is the percentage of nitrogen by mass in each compound? (Divide the formula mass of the nitrogen in each compound by the formula mass of the compound and then express the result as a percentage.)