A ehite chemical compound becomes hard on mixing proper quantity of water. It is also used to maintain joints in a fixed position. Name the chemical compound and write its chemical formula. Chemical equation to show what happens when water is added to this compound in proper quantity.

Explanation

The chemical compound is Plaster of Paris. Its chemical formula is `2CaSO_(4).H_(2)OorCaSO_(4).1//2H_(2)O.` On adding a small amount of water, it changes to Gypsum which is quite hard.
`underset("Pastere of Paris")(CaSo_(4)1//2)H_(2)O+3//2H_(2)O toCaSO_(4).underset("Gypsum")(2H_(2)O)`