C-08-Q111mediumsingle_mcqChemical formula of gypsum is —aCaCOX3\ce{CaCO3}CaCOX3bCaSOX4 ⋅ 2 HX2O\ce{CaSO4.2H2O}CaSOX4⋅2HcFeX3OX4\ce{Fe3O4}FeX3OXdSiOX2\ce{SiO2}SiOX2