Net Ionic Equation for Acid-Carbonate Reaction Steps:

• Write the molecular equation: CaCO3(s) + 2HCl(aq) → CaCl2(aq) + H2O(l) + CO2(g).
• Dissociate strong electrolyte HCl into 2H+(aq) + 2Cl-(aq) and CaCl2 into Ca2+(aq) + 2Cl-(aq); CaCO3 remains undissociated as solid.
• Form complete ionic equation: CaCO3(s) + 2H+(aq) + 2Cl-(aq) → Ca2+(aq) + 2Cl-(aq) + H2O(l) + CO2(g).
• Cancel spectator ions (2Cl-) to get net ionic equation: CaCO3(s) + 2H+(aq) → Ca2+(aq) + H2O(l) + CO2(g).

Why C is correct:

• It represents the net ionic equation by excluding spectators and showing only the essential reaction where H+ reacts with solid CaCO3 to form Ca2+, H2O, and CO2, per standard ionic equation rules.

Why the others are wrong:

• A: Full molecular equation, includes undissociated HCl and CaCl2.
• B: Incorrectly dissociates insoluble CaCO3 into ions on reactant side.
• D: Adds extraneous CO32-(aq) on product side, violating conservation of charge and mass.

Final answer: C