Assertion : Vulcanization increases the hardness of natural rubber.
Reason: Vulcanization introduces the polysulphide bridges at reactive sites.

Options

A. Assertion and reason both are correct statements and reason is correct explanation for assertion.
B. Assertion and reason both are correct statements but reason is not correct explanation for assertion.
C. Assertion is correct statement but reason is wrong statement.
D. Assertion is wrong statement but reason is correct statement.

Answer

To analyze the assertion and reason provided in the question, we can break it down into a step-by-step solution.

### Step 1: Understand the Assertion
The assertion states that "Vulcanization increases the hardness of natural rubber."
- **Explanation**: Vulcanization is a chemical process that involves heating rubber with sulfur. This process creates cross-links between the polymer chains, which increases the hardness and elasticity of the rubber.

### Step 2: Understand the Reason
The reason states that "Vulcanization introduces the polysulphide bridges at reactive sites."
- **Explanation**: During vulcanization, sulfur atoms form cross-links (or bridges) between the long chains of rubber molecules. These can be polysulfide bridges, which are formed when multiple sulfur atoms are involved in the cross-linking process. This cross-linking is what contributes to the increased hardness of the rubber.

### Step 3: Evaluate the Assertion and Reason
- **Assertion Evaluation**: The assertion is correct because vulcanization indeed increases the hardness of natural rubber.
- **Reason Evaluation**: The reason is also correct because vulcanization does introduce polysulfide bridges at the reactive sites of the rubber molecules.

### Step 4: Conclusion
Both the assertion and the reason are correct, and the reason accurately explains why the assertion is true.

### Final Answer
Both the assertion and the reason are correct, and the reason correctly explains the assertion.

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