An unknown sample of Cu2 gave an absorbance of 0.262 in an atomic absorption analysis. Then 1.00 mL of solution containing 100.0 ppm ( g/mL) Cu2 was mixed with 95.0 mL of unknown, and the mixture was diluted to 100.0 mL in a volumetric flask. The absorbance of the new solution was 0.500. (a) Denoting the initial, unknown concentration as [Cu2] i, write an expression for the final concentration, [Cu2] f, after dilution. Units of concentration are ppm. (b) In a similar manner, write the final concentration of added standard Cu2, designated as [S] f. (c) Find [Cu2] i in the unknown.