HNO3+CaCO3

Balanced molecular equation: 2 HNO3 + CaCO3 → Ca(NO3)2 + CO2 + H2O

Notes:

• This is an acid-carbonate reaction with evolution of CO2 gas.
• Net ionic equation: 2 H+ + CO3^2- → CO2 + H2O

Full ionic form (for completeness): 2 H+(aq) + 2 NO3-(aq) + CaCO3(s) → Ca2+(aq) + 2 NO3-(aq) + CO2(g) + H2O(l)

Calcium and nitrate ions are spectators in solution; the net ionic shows the actual acid–carbonate reaction. If you want, I can walk through the balancing steps.