3. Twenty dietary iron tablets with a total mass of 22.131 g were ground and mixed thoroughly. Then 2.998 g of the powder was dissolved in HNO3 and heated to convert all of the iron to Fe(III). Addition of NH3 caused quantitative precipitation of Fe2O3 xH2O, which was ignited to give 0.264 g Fe2O3. What is the average mass of FeSO4 7H2O in each tablet (2 points)? .