You are given an impure sample of copper sulphate. How would you obtain pure copper sulphate crystals from it? Name the technique and describe the process.

To obtain pure copper sulphate crystals from an impure sample, the technique of crystallization would be used. 

Process:

1. Dissolution: Dissolve the impure copper sulphate in the minimum amount of water at a higher temperature to form a concentrated solution. 
2. Filtration: Filter the hot solution to remove any insoluble impurities. 
3. Cooling: Allow the hot, saturated solution to cool slowly and undisturbed at room temperature. As the solution cools, the solubility of copper sulphate decreases, and the pure copper sulphate starts to crystallize out. 
4. Separation and Drying: Separate the crystals from the mother liquor by filtration and dry them between filter papers.