Statement 1 : Crystals of hydrated calcium sulphate gypsum : CaSO4.2H2O are soft and easily cleaved.Statement 2 : Crystals of anhydrous calcium sulphate (anhydride : CaSO4) are very hard and very difficult to cleave.

Within the Ca2+/SO42− layers, the ions are held together by strong electrovalent bonds. But these separated Ca2+/SO42− layers are linked by relative weak H - bond. The weakest H - bonds link SO42− ions in the intermediate region. Consequently, the gypsum can be readily cleaved and stretched along the layer of water molecules.Anhydride has a completely ionic structure involving only Ca2+ and SO42−  ions.