C-12-Q051mediumsingle_mcq2NH4Cl+Ca(OH)2→Δ?\mathrm{2NH_4Cl + Ca(OH)_2 \xrightarrow{\Delta} ?}2NH4Cl+Ca(OH)2Δ?a2NH3+CaCl2+2H2O\mathrm{2NH_3 + CaCl_2 + 2H_2O}2NH3+CaCl2+2H