118. Solving a chemistry problem

26. The molar absorption coefficient of the water-soluble complex of nickel with dimethylglyoxime at 470 nm is 1.30*104. Calculate: a) the optical density of the solution of the complex, 1 ml of which contains 1 µg of nickel, with the thickness of the absorbing layer l = 1.00 cm; b) passing it; c) the concentration of nickel in the solution (µg/ml), if the optical density of the solution containing nickel dimethylglyoximate and placed in a cuvette with l = 3.00 cm is 0.190 at 470 nm. Mol. mass (Ni) 58.69.