C-10-Q060mediumsingle_mcq2PbS+3O2→Δ?\mathrm{2PbS + 3O_2 \xrightarrow{\Delta} ?}2PbS+3O2Δ?a2PbO+2SO2\mathrm{2PbO + 2SO_2}2PbO+2SO2b2Pb+2SO3\mathrm{2Pb + 2SO_3}