77. Solving a chemistry problem

4. Nickel in solution was determined by spectrophotometric method at λ=445 nm after its reaction with dimethylglyoxime in an alkaline medium. The optical density of the test solution in a cell 10 mm thick is 0.650. The molar absorption coefficient of the nickel complex with dimethylglyoxime (under the conditions under which the determination was carried out) is 1.5*104 dm3mol3cm-1. Calculate concentration (mol/dm3 and µg/ml)
Ni2 ions in the test solution.