A. synthesis.
b. decomposition.
c. double replacement.
d. single replacement.
me

Double replacement

Explanation:

The given reaction is double replacement reaction.

CaCO₃ + 2HCl  → CaCl₂ + H₂CO₃

Double replacement:

It is the reaction in which two compound exchange their ions and form new compounds.

AB + CD → AC +BD

while,

Synthesis reaction:

It is the reaction in which two or more simple substance react to give one or more complex product.

Decomposition:

It is the reaction in which one reactant is break down into two or more product.

AB → A + B

Single replacement:

It is the reaction in which one elements replace the other element in compound.

AB + C → AC + B

the answer is true.

nacl is added to the aqueous of what? ? in order to get a proper answer you have to specify the exact composition of the aqueous solution.