Which law states that mass is conserved in a chemical reaction, ensuring that chemical equations are balanced?

• A. Law of Multiple Proportions
• B. Law of Definite Proportions
• C. Dalton's Atomic Theory
• D. Law of Conservation of Mass

Answer: (D)

Verified step by step guidance

1. Understand that the question is asking about the fundamental law that ensures mass remains constant during a chemical reaction, which is essential for balancing chemical equations.
2. Recall that the Law of Conservation of Mass states that mass cannot be created or destroyed in a chemical reaction; it only changes forms.
3. Recognize that this law implies the total mass of reactants must equal the total mass of products, which is why chemical equations must be balanced.
4. Differentiate this law from others: the Law of Multiple Proportions deals with ratios of elements in compounds, the Law of Definite Proportions concerns fixed composition of compounds, and Dalton's Atomic Theory explains atomic structure and behavior.
5. Conclude that the Law of Conservation of Mass is the correct law that guarantees mass conservation and the necessity of balancing chemical equations.