Question

When a crystal of copper sulphate is placed at the bottom of a beaker containing water , the water slowly turns blue. Why ?

Answer 1

this is due to the movement of water particles. due to this, the copper sulphate particles and water molecules get mix with each other by the process of diffusion. due to this diffusion, when a crystal of copper sulphate is placed at the bottom of a beaker containing water , the water slowly turns blue. 

Answer 2

this due to particles of liquid move slowly

as compared to gases. so slowly turns blue.