Question

The coefficients of a balanced version of the equation of reaction involving hydrochloric acid and calcium carbonate to give the respective products are:
2,1,1,1,2
2,1,1,1,1
1,2,1,1,1
1,3,1,2,1

Answer 1

2HCl + CaCO3 = CaCl2 + H2O + CO2

So that the coefficients are 2,1,1,1,1.