?$ \ \text {CaCO}_3+2\ \text {HCl}\xlongequal[\ \ \ \ \ \ ]{\ \ \ \ \ \ }$?
?$ \ \text {CaCl}_2+\ \text {H}_2\ \text {O}+\ \text {CO}_2↑$?
?$ \ \text {Na}_2\ \text {CO}_3+2\ \text {HCl}\xlongequal[]{}$?
?$ 2\ \text {NaCl}+\ \text {H}_2\ \text {O}+\ \text {CO}_2↑$?