Which of the following laws deals with mass of reactants and products during chemical reactions?

Options

A. Law of definite proportions
B. Law of conservation of energy
C. Law of conservation of mass
D. Law of reciprocal proportions

Explanation

To solve the question regarding which law deals with the mass of reactants and products during chemical reactions, we can follow these steps:

### Step 1: Understand the Question
The question asks which law relates to the mass of reactants and products in chemical reactions. We need to identify the correct law from the options provided.

### Step 2: Identify the Relevant Laws
We have several laws related to chemical reactions:
1. **Law of Conservation of Mass**
2. **Law of Definite Proportions**
3. **Law of Conservation of Energy**
4. **Law of Reciprocal Proportions**

### Step 3: Analyze Each Law
- **Law of Conservation of Mass**: This law states that in a closed system, the mass of reactants before the reaction is equal to the mass of products after the reaction. This means that mass is conserved during chemical reactions.

- **Law of Definite Proportions**: This law states that a chemical compound always contains the same proportion of elements by mass, but it does not specifically deal with the total mass of reactants and products.

- **Law of Conservation of Energy**: This law states that energy cannot be created or destroyed, only transformed. It does not directly relate to mass in chemical reactions.

- **Law of Reciprocal Proportions**: This law deals with the ratios of masses of different elements that combine with a fixed mass of another element, but it does not address the total mass of reactants and products.

### Step 4: Conclusion
Based on the analysis, the **Law of Conservation of Mass** is the law that specifically deals with the mass of reactants and products during chemical reactions. Therefore, the correct answer is the **Law of Conservation of Mass**.

### Final Answer
The law that deals with the mass of reactants and products during chemical reactions is the **Law of Conservation of Mass**.

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