50. Solving a chemistry problem

3. A sample of an organic compound weighing 2.158 mg was subjected to pyrolysis, when all the sulfur passes into hydrogen sulfide. The pyrolysis products were passed through an electrolytic cell filled with mercury nitrate. Solution resistance increased by ΔR=460 Ohm. In the same way, standard substances containing sulfur were measured and the corresponding ΔR values were measured:
Sulfur content in the sample, mg 0.240 0.260 0.280 0.300
ΔR•10-6, Ohm 450 480 510 540
Build a calibration graph and calculate the mass fraction of sulfur in an organic compound