Final answer:
The statement is true: the law of conservation of mass ensures that during a chemical reaction, matter is neither created nor destroyed, preserving the total mass of the reactants in the products. Option A is correct.
Step-by-step explanation:
The student asked whether the statement 'The law of conservation of mass states that matter cannot be gained or lost during a chemical reaction' is true or false. The correct answer is true. The law of conservation of mass states that during a chemical reaction, the total mass of the products must be equal to the total mass of the reactants.
This implies that matter, or mass, is neither created nor destroyed in the process of a chemical reaction. For example, if you start with 20 grams of reactants, the total mass of the products after the reaction will also be 20 grams, demonstrating that the mass is conserved.
The law of conservation of mass was established by Antoine Lavoisier in the 1789, and it plays a crucial role in the field of chemistry by ensuring that mass is accounted for through transformations in a closed system.