Which statement best describes the equation CaCO3 + 2HCl → CaCl2 + CO2 + H2O? CaCO3 is a reactant; it is present before the reaction occurs.
CaCl2 is a reactant; it is present before the reaction occurs.
CO2 is a reactant because it is most likely a gas.
H2O is a reactant because it is most likely a liquid.

First answer

Explanation:

Reactants are always on the left side of the equation.  So the first answer must be the correct one since CaCO3 is the only one found on the left side.

geosphere and hydrosphere.

this is because the geosphere has to do with geological events, while the hydrosphere controls all water on earth.