Why hydrated copper sulphate is blue while anhydrous copper sulphate is white?

Explanation

In `CuSO_4`. `5H_2O` four water, molecules are present as ligands, in the rpesence iof thse lagands d-orbitals are no longer degenerate in energy. Hence d-d transition takes place absorbing red wavelength. The complementary place absorbing colour, viz, blue is reflected. In anhydrous `CuSO_4`, d-orbitals remain degenerate. Hence no d-d transition can occur. The white light is completely reflected back. Hence it looks white