Which of the following polymers is not correctly matched ?

Options

A. Formation of dacron-Step growth polmerisation
B. Formation of polytetrafluoroethene- step growth polymerisation
C. Formation of polythene-Chain growth polymerisation in presence of benzoyl peroxide
D. Formation of polyacylonitrile - Chain growth polymerisation in presence of peroxide

Explanation

To solve the question "Which of the following polymers is not correctly matched?", we need to analyze the given options based on the types of polymerization processes involved in their formation.

### Step-by-Step Solution:

1. **Identify Types of Polymers**:
- There are two main types of polymers:
- **Addition Polymers**: Formed through chain growth polymerization.
- **Condensation Polymers**: Formed through step growth polymerization.

2. **List Examples of Each Type**:
- **Addition Polymers**: Examples include polytetrafluoroethene (PTFE), polyethylene, and polyacrylonitrile.
- **Condensation Polymers**: Examples include Dacron (a type of polyester) and Nylon.

3. **Evaluate Each Option**:
- **Option A**: Formation of Dacron by step growth polymerization.
- Dacron is indeed a condensation polymer, so this match is correct.
- **Option B**: Formation of polytetrafluoroethene by step growth polymerization.
- Polytetrafluoroethene is an addition polymer, so it should be formed by chain growth polymerization. This match is incorrect.
- **Option C**: Formation of polyethylene by chain growth polymerization in the presence of benzoyl peroxide.
- Polyethylene is an addition polymer, and its formation through chain growth polymerization is correct.
- **Option D**: Formation of polyacrylonitrile by chain growth polymerization in the presence of peroxide.
- Polyacrylonitrile is also an addition polymer, and its formation through chain growth polymerization is correct.

4. **Conclusion**:
- The incorrectly matched polymer is **Option B**: Formation of polytetrafluoroethene by step growth polymerization.

### Final Answer:
The polymer that is not correctly matched is **Option B: Formation of polytetrafluoroethene by step growth polymerization**.

---