Which statement best describes the equation caco3 + 2hcl → cacl2 + co2 + h2o?
a. caco3 is a reactant; it is present before the reaction occurs.
b. cacl2 is a reactant; it is present before the reaction occurs.
c. co2 is a reactant because it is most likely a gas.
d. h2o is a reactant because it is most likely a liquid.

Option (A) is the correct answer.

Explanation:

It is known that while writing a chemical reaction equation, reactants are written on left hand side whereas products are written on right hand side.

For example,

Here, both and HCl are the reactants whereas , and are the products.

Hence, we can conclude that the statement is a reactant; it is present before the reaction occurs, best describes the given equation.

yes the answer is total mass in unchanged   : )