C-10-Q159mediumsingle_mcqH2SO4+Ca(OH)2→?\mathrm{H_2SO_4 + Ca(OH)_2 \to ?}H2SO4+Ca(OH)2→?aCaSO4+2H2O\mathrm{CaSO_4 + 2H_2O}CaSO4+2H2ObCaS+H2O\mathrm{CaS + H_2O}CaS+H2OcCaO+H2S\mathrm{CaO + H_2S}CaO+H2SdCa(HSO4)2\mathrm{Ca(HSO_4)_2}Ca(HSO4)2