Answer:
2HCl + CaCO3 => CaCl2 + H2O+ CO2
Step-by-step explanation:
to balance the equation, number of atoms of each elements both sides of the arrow must be equal.
in this equation Cl and H both have 2 atoms in right hand side equation, while in left side of arrow both have only one atom, so to make it balance we have to make it equal both sides, hence multiply HCl by 2.