which of the following compounds contains the lowest percentage by mass of nitrogen?

Question

1) NH4NO3
2) (NH4)2 SO4
3) NaNO3
4) NH3

can someone please help me??what method should i use?how do i do this?

Find the molar mass of each compound by adding the molar masses of every atom (including N) in the compound and divide the the total molar mass of nitrogen (only N) in the compound by that value. (14.0067* (# of N atoms))/(compound molar mass) This should give you each percentage of mass of nitrogen. Good Luck!!!