Assertion : Bakelite is a thermosetting polymer.
Reason : Bakelite is formed by cross- linking of novolac and formaldehyde .

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion .
B. If both assertion and reason are true but reason is not the correct explanation of assertion .
C. If assertion is true but reason is false.
D. If both assertion and reason are false.

Answer

To solve the assertion-reason question regarding Bakelite, we will analyze both the assertion and the reason step by step.

### Step 1: Understand the Assertion
The assertion states that "Bakelite is a thermosetting polymer."

**Explanation:**
Thermosetting polymers are a class of polymers that, once set into a given shape, cannot be remolded or reheated to change their form. This is due to the presence of cross-linking between polymer chains, which provides structural integrity and stability.

### Step 2: Understand the Reason
The reason states that "Bakelite is formed by cross-linking of novolac and formaldehyde."

**Explanation:**
Bakelite is indeed formed through a chemical reaction involving phenol and formaldehyde. When phenol reacts with formaldehyde, it can form a linear polymer known as novolac. Upon further heating and in the presence of additional formaldehyde, novolac undergoes cross-linking to form Bakelite, which is a thermosetting polymer.

### Step 3: Analyze the Relationship
Now, we need to determine if the reason correctly explains the assertion.

- The assertion is true: Bakelite is a thermosetting polymer.
- The reason is also true: Bakelite is formed by the cross-linking of novolac and formaldehyde.

Since the reason provides a correct explanation for the assertion, we can conclude that both the assertion and the reason are true, and the reason is indeed the correct explanation of the assertion.

### Final Conclusion
Both the assertion and the reason are true, and the reason correctly explains the assertion.