What is the balanced chemical equation for the reaction used to calculate ΔH∘f of CaCO3(s) ? If fractional co?

What is the balanced chemical equation for the reaction used to calculate ΔH∘f of CaCO3(s) ?

If fractional coefficients are required, enter them as a fraction (i.e. 1/3). Indicate the physical states using the abbreviation (s), (l), or (g) for solid, liquid, or gas, respectively. Use (aq) for aqueous solution.
Express your answer as a chemical equation.

The standard enthalpy of formation (ΔH∘f) is the enthalpy change that occurs when exactly 1 mol of a compound is formed from its constituent elements under standard conditions. The standard conditions are 1 atm pressure, a temperature of 25 ∘C , and all the species present at a concentration of 1 M . A "standard enthalpies of formation table" containing ΔH∘f values might look something like this:
Substance ΔH∘f
H(g) 218 kJ/mol
H2(g) 0 kJ/mol
Ca(s) 0 kJ/mol
Ca2 (aq) −543 kJ/mol
C(g) 71 kJ/mol
C(s) 0 kJ/mol
N(g) 473 kJ/mol
O2(g) 0 kJ/mol
O(g) 249 kJ/mol
S2(g) 129 kJ/mol