What is the colour of the mixture of copper (II) salt and iron (III) salt solution?

Answer 1

Aqueous solutions of copper(II) are usually blue. Aqueous solutions of iron(III) are usually brownish yellow. So a mixture of the two, provided they are in roughly equal proportions, will give a colour intermediate between the two - a sort of olive colour, I suppose.

Note that the colour of aqueous copper(II) depends, to a certain extent, on the nature of the anion. For instance, a concentrated aqueous solution of copper(II) chloride is bright green, because of the presence of the CuCl4(--) ion, but this changes through bluish-green, greenish blue and then to blue as it is diluted.