Acids Bases and Salts MCQs The chemical formula of Plaster of Paris is December 28, 2021 Q. The chemical formula of Plaster of Paris is CaSO₄,1/2H₂OCaSO₄, 2H₂OCaSO₄, H₂OCaSO₄, 3H₂O Answer: CaSO₄,1/2H₂O