Solution:Concept- If the reactants and products of a chemical reaction have the same number of atoms and total charge for each component of the reaction, the equation for the reaction is said to be balanced. The mass and charge balances on both sides of the reaction are therefore equivalent.
A balanced chemical reaction is one in which the quantity of reactant atoms and product atoms participating in the reaction are consistently equal.
The formula of gypsum is and plaster of Paris is calcium sulphate hemihydrate i.e The chemical reaction is as follows;
Hence, the correct answer is (1).