A: Polybutadiene is an example of chain growth polymer.
R: Copolymerization of butadiene and styrene gives Buna-S.

Options

A. If both Assertion & Reason are true and the reason is the correct explanation of the assertion, then mark 1.
B. If both Assertion & Reason are true but the reason is not the correct explanation of the assertion, then mark 2.
C. If Assertion is true statement but Reason is false, then mark 3.
D. If both Assertion and Reason are false statements the mark 4.

Answer

To analyze the given statements about polybutadiene and Buna-S, we will break down the problem into steps.

### Step 1: Understand the Assertion
The assertion states that "Polybutadiene is an example of a chain growth polymer."

**Explanation**:
- Chain growth polymers are formed by the addition of monomers with unsaturated bonds, such as alkenes.
- Polybutadiene is synthesized from the polymerization of butadiene, which is an unsaturated hydrocarbon (C4H6) with double bonds.
- Therefore, the assertion is true since polybutadiene is indeed a chain growth polymer.

### Step 2: Understand the Reason
The reason states that "Copolymerization of butadiene and styrene gives Buna-S."

**Explanation**:
- Buna-S is a copolymer made from the copolymerization of two different monomers: butadiene and styrene.
- The process involves the addition of these two monomers to form a polymer that has properties of both components.
- This statement is also true since Buna-S is a well-known synthetic rubber derived from this copolymerization.

### Step 3: Evaluate the Connection Between Assertion and Reason
Now, we need to determine if the reason justifies the assertion.

**Analysis**:
- While both statements are true, the reason does not directly explain why polybutadiene is a chain growth polymer.
- The assertion is about the nature of polybutadiene, while the reason discusses a different polymer (Buna-S) that involves a different process (copolymerization).
- Therefore, the reason does not provide a justification for the assertion.

### Conclusion
- The assertion is true: Polybutadiene is a chain growth polymer.
- The reason is true: Copolymerization of butadiene and styrene gives Buna-S.
- However, the reason does not justify the assertion.

### Final Answer
- Assertion (A) is true.
- Reason (R) is true, but it does not justify (A).