Stock solution A is prepared by dissolving 182 mg of ferrous ammonium sulfate in water and diluting to volume in a 500-mL volumetric flask. Calculate the concentration of iron, in ppm, in stock solution A.

Answer 1

percent Fe in Fe(NH4)2(SO4)2.6H2O Note this is the common hydrated salt, if different, you need to recalculate.
percentFe=2*55.8/392
mass iron in 182g= percentFe*182=51.8mg
concentration 51.8mg/500g or 51.8mg/500e3mg or 51.8/.5e6 or 10.3 ppm