How can I find the percent compositions of N2S2?

To find the of N₂S₂, you divide the total mass of each atom by the molecular mass and multiply by 100 %.
% by mass = ##”mass of component”/”total mass”## × 100 %
Mass of 2 N atoms = 2 N atoms × ##(14.01″u”)/(1″N atom“)## = 28.02 u.
Mass of 2 S atoms = 2 S atoms × ##(32.06″u”)/(1″S atom“)## = 64.12 u
Mass of 1 N₂S₂ molecule = (28.02 + 64.12) u = 92.14 u
% of N = ##”mass of N”/”total mass”## × 100 % = ##(28.02″u”)/(92.14″u”)## × 100 % =30.41 %
% of S = ##”mass of S”/”total mass”## × 100 % = ##(64.12″u”)/(92.14″u”)## × 100 % =69.59 %