when a slice of potato kept for sometime a change in colour is observed .why

Q. Potato slices are immersed in a series of solution of different osmotic concentrations. No change in volume or weight is observed with slices in a 0.3 M solution. Therefore the osmotic concentration of vacuolar sap is

Q. On keeping iron nails in blue colour copper sulphate solution it is observed that the colour of the solution turns green after sometimes give reason for this colour change in the type of reaction

Q. Potato slices are immersed in a series of solution of different osmotic concentrations. No change in volume or weight is observed with slices in a 0.3 M solution. The osmotic concentration of vacuolar sap, therefore, is