Which of the following polymers, need atleast one diene monomer for their preparation?

Options

A. Dacron
B. Buna-s
C. Neoprene
D. Novalac

Explanation

To determine which of the given polymers requires at least one diene monomer for their preparation, we will analyze the monomers used in each polymer.

### Step-by-Step Solution:

1. **Understanding Diene Monomers**:
- A diene is a type of hydrocarbon that contains two double bonds. Common examples include 1,3-butadiene.

2. **Analyzing Each Polymer**:
- **Dacron**:
- Dacron is made from ethylene glycol and terephthalic acid.
- Ethylene glycol (C2H6O2) is a diol and does not contain any double bonds.
- Terephthalic acid (C8H6O4) is a dicarboxylic acid and also does not contain any double bonds.
- **Conclusion**: Dacron does not contain a diene monomer.

- **Buna-S**:
- Buna-S is made from 1,3-butadiene and styrene.
- 1,3-butadiene (C4H6) is a diene as it has two double bonds.
- Styrene (C8H8) is an alkene but not a diene.
- **Conclusion**: Buna-S contains a diene monomer.

- **Neoprene**:
- Neoprene is made from chloroprene.
- Chloroprene (C4H5Cl) is structurally 2-chloro-1,3-butadiene, which is a diene.
- **Conclusion**: Neoprene contains a diene monomer.

- **Novolac**:
- Novolac is made from phenol and formaldehyde.
- Phenol (C6H5OH) and formaldehyde (CH2O) do not contain any double bonds.
- **Conclusion**: Novolac does not contain a diene monomer.

3. **Final Conclusion**:
- From the analysis, the polymers that require at least one diene monomer for their preparation are:
- **Buna-S** (Option 2)
- **Neoprene** (Option 3)

### Answer:
The polymers that need at least one diene monomer for their preparation are **Buna-S** and **Neoprene**.

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