Đáp án đúng: A
1, 2, 5 đúng
$\begin{array}{l}\text{(1)}\,\text{C}{{\text{O}}_{\text{2}}}\,\text{+}\,\text{2}{{\text{H}}_{\text{2}}}\text{O}\,\text{+}\,\text{NaAl}{{\text{O}}_{\text{2}}}\,\xrightarrow{{}}\,\text{Al(OH}{{\text{)}}_{\text{3}}}\downarrow \,\text{+}\,\text{NaHC}{{\text{O}}_{\text{3}}}\\\text{(2)}\,\text{3N}{{\text{H}}_{\text{3}}}\,\text{+}\,\text{3}{{\text{H}}_{\text{2}}}\text{O}\,\text{+}\,\text{AlC}{{\text{l}}_{\text{3}}}\,\xrightarrow{{}}\,\text{Al(OH}{{\text{)}}_{\text{3}}}\downarrow \,\text{+}\,\text{3N}{{\text{H}}_{\text{4}}}\text{Cl}\\\text{(3)}\,\text{AlO}_{\text{2}}^{\text{-}}\,\text{+}\,\text{4}{{\text{H}}^{\text{+}}}\,\xrightarrow{{}}\,\text{A}{{\text{l}}^{\text{3+}}}\,\text{+}\,\text{2}{{\text{H}}_{\text{2}}}\text{O}\\\text{(4)}\,\text{A}{{\text{l}}^{\text{3+}}}\,\text{+}\,\text{4O}{{\text{H}}^{\text{-}}}\,\xrightarrow{{}}\,\text{Al(OH)}_{\text{4}}^{\text{-}}\\\text{(5)}\,\text{C}{{\text{a}}^{\text{2+}}}\,\text{+}\,\text{HCO}_{\text{3}}^{\text{-}}\text{+}\,\text{O}{{\text{H}}^{\text{-}}}\,\xrightarrow{{}}\,\text{CaC}{{\text{O}}_{\text{3}}}\downarrow \,\text{+}\,{{\text{H}}_{\text{2}}}\text{O}\\\text{(6)}\,\text{2C}{{\text{O}}_{\text{2}}}\,\text{+}\,\text{Ca(OH}{{\text{)}}_{\text{2}}}\,\xrightarrow{{}}\,\text{Ca(HC}{{\text{O}}_{\text{3}}}{{\text{)}}_{\text{2}}}\end{array}$