Answer: Mass of the reactant is 4 grams.
Step-by-step explanation:
It is given that 4 grams of product is produced in a chemical reaction ad we need to find the mass of reactant consumed, so we will follow Law of conservation of mass.
This law states that mass can neither be created, nor be destroyed but it can only be transformed from one form to another. Total mass in the reaction remains conserved.
Hence, mass of the reactant is 4 grams.