Question

even one or two crystals of copper sulphate can make the solution in water blue. why ?​

Answer 1

$\huge\color{cyan}\boxed{\colorbox{black}{AnSwEr}}$

When we heat the crystals, this water is removed and the salt turns white. If you moisten the crystals again with water, you will find that blue colour of the crystals reappears.

Answer 2

Answer:

When we heat the crystals, this water is removed and the salt turns white. If you moisten the crystals again with water, you will find that blue colour of the crystals reappears.