Calcium Sulphate

Which of the following statements with regard to Portland cement are correct? 1. Silica imparts strength to cement. Alumina makes the cement quick setting 3. Excess of lime increases the strength of cement. 4. Calcium sulphate decreases the initial setting time of cement. Select the correct answer using the code given below :

Setting of plaster of Paris involves: (A) The oxidation with atmospheric oxygen (B) The removal of water to form anhydrous calcium sulphate (C) The hydration to form the orthorhombic form of gypsum (D) The reaction with atmospheric carbon dioxide gas

Consider the following statements. l. Permanent hardness of water is removed by treatment with washing soda. ll. Platinum and palladium can adsorb large volumes of hydrogen. Ill. Washing soda reacts with soluble magnesium and calcium sulphate to form insoluble carbonates. Choose the correct statement(s).