89. Solving a chemistry problem

The molar light absorption coefficient of the MoO(SCN)52- complex in isoamyl alcohol at λ dff = 475 nm is ε = 1.50*104. Calculate the minimum mass fraction (%) of molybdenum in the soil that can be determined by this method if molybdenum is extracted from a sample of soil weighing 20.00 g in 200.0 ml of an oxalate buffer solution. 150.0 ml of the filtrate are taken and, after appropriate work-up, the MoO(SCN)52 formed is extracted with 15.00 ml of isoamyl alcohol. The extract is photometered in a cuvette I = 3.0 cm. The minimum optical density is taken equal to 0.020.