Answer:
(3) Equals the mass of CaO plus the mass of CO₂
Step-by-step explanation:
The important principle to remember is the Law of Conservation of Mass — the total mass of the reactants must equal the total mass of the products.
Reactants ⟶ products
CaCO₃ ⟶ CaO + CO₂
Mass of CaCO₃ = Mass of CaO + mass of CO₂