water added to sand and salt is a physical change whereasit added to cement is a chemical change.justify

When water is added to mixture of sand and salt a solution is formed in which salt get dissolved and sand remain as such. This is a physical change as we get back salt and sand from solution by filtration followed by evaporation.

Cement is a mixture of different chemicals like CaO, MgO, SiO₂, Al₂O₃, Fe₂O₃ and SO₃When water is added to cement its constituents get hydrated and hence their molecules form bond with each other to form a hard rock. This is known as setting of cement. we can not get original cement powder from this set cement. More over its property also changed. Hence it is a chemical change.