Đáp án đúng: B
2H+ + CO2↑ + H2O.
$\text{N}{{\text{a}}_{\text{2}}}\text{C}{{\text{O}}_{\text{3}}}\,\text{+}\,\text{2HCl}\,\xrightarrow{{}}\,{{\text{H}}_{\text{2}}}\text{O}\,\text{+}\,\text{C}{{\text{O}}_{\text{2}}}\uparrow \,\text{+}\,\text{2NaCl}$
$\text{2N}{{\text{a}}^{\text{+}}}\,\text{+}\,\text{CO}_{\text{3}}^{\text{2-}}\,\text{+}\,\text{2}{{\text{H}}^{\text{+}}}\,\text{+}\,\text{2C}{{\text{l}}^{\text{-}}}\,\xrightarrow{{}}\,{{\text{H}}_{\text{2}}}\text{O}\,\text{+}\,\text{C}{{\text{O}}_{\text{2}}}\uparrow \,\text{+}\,\text{2N}{{\text{a}}^{\text{+}}}\,\text{+}\,\text{2C}{{\text{l}}^{\text{-}}}$
$\text{2}{{\text{H}}^{\text{+}}}\,\text{+}\,\text{CO}_{\text{3}}^{\text{2-}}\,\xrightarrow{{}}\,{{\text{H}}_{\text{2}}}\text{O}\,\text{+}\,\text{C}{{\text{O}}_{\text{2}}}\uparrow $
