Matter is neither created nor destroyed in the course of any chemical reactions is a statement of the law of

Step 1: Analyze the question The statement says matter is neither created nor destroyed during a chemical reaction. We need to match it to the correct law of chemical combination.

Step 2: Review the laws

• Law of conservation of mass (Lavoisier): The total mass of reactants equals the total mass of products. Matter is neither created nor destroyed in a chemical reaction.
• Law of combining volumes (Gay-Lussac): Gases react in volumes that are in simple whole-number ratios, at the same temperature and pressure.
• Law of definite proportion (constant composition, Proust): A pure compound always contains the same elements in the same proportion by mass.
• Law of multiple proportions (Dalton): When two elements form more than one compound, the masses of one element that combine with a fixed mass of the other are in simple whole-number ratios.
• Law of reciprocal proportions (Richter): The masses of two elements that separately combine with a fixed mass of a third element are in the same ratio (or a simple multiple of it) as when they combine with each other.

Step 3: Match the statement "Matter is neither created nor destroyed" is about total mass staying the same before and after a reaction. This is the law of conservation of mass.

Example: When 12 g of carbon burns completely in 32 g of oxygen, 44 g of carbon dioxide forms. The mass is 12 + 32 = 44 g on both sides, so nothing was created or lost.

Answer: B. conservation of mass

Exam tip: Look for key words in the question:

• "created or destroyed" → conservation of mass
• "fixed composition" → definite proportion
• "volumes of gases" → combining volumes
• "more than one compound of the same elements" → multiple proportions