3. The content of samarium in cerium dioxide was determined by the addition method. A standard solution of samarium nitrate was prepared by dissolving 115.8 mg of Sm2O3 in nitric acid. The dry residue after evaporation was dissolved in water and diluted to 100.0 ml (solution A). Then 0.10 ml of solution A was diluted with water to 100.0 ml (solution B).
A sample of СеО2 weighing t mg was mixed with sodium sulfate and divided into two equal parts. One of them was injected with 0.5 ml of solution B; the mixture was dried and calcined. The luminescence intensity of the obtained phosphors (peak height, mm) turned out to be:
Option 1 2 3
m, mg 200 170 190
h, mm 50 40 30
hx + 3, mm. 70 60 55
Calculate the mass fraction (%) of samarium in cerium dioxide.