Which of the following statements is not ture?

Options

A. Natural rubber is 1,4- polymer of isoprene
B. In vulcanization, the formation of sulphur bridges between different chains make rubber harder and stronger
C. Natural rubber has the trans configutation at every double bond
D. Buna-S is a copolymer of butadiene and styrene

Answer

To determine which statement is not true regarding polymers, particularly rubber and its properties, we will analyze each statement based on the information provided in the video transcript.

### Step-by-Step Solution:

1. **Understanding the First Statement:**
- The first statement refers to the 1,4-polymer of isoprene.
- Isoprene (2-methyl-1,3-butadiene) polymerizes to form natural rubber, which is primarily in the cis-1,4 configuration.
- **Conclusion:** This statement is true.

2. **Understanding the Second Statement:**
- The second statement discusses vulcanization, which is the process of heating rubber with sulfur to create cross-links between polymer chains.
- This process indeed makes rubber stronger and harder.
- **Conclusion:** This statement is true.

3. **Understanding the Third Statement:**
- The third statement mentions the properties of natural rubber, specifically its cis form of polyisoprene.
- It is correct that natural rubber is primarily composed of cis-1,4-polyisoprene, while the trans form is known as gutta-percha.
- **Conclusion:** This statement is true.

4. **Understanding the Fourth Statement:**
- The fourth statement refers to BUNA-S, which is a copolymer of butadiene and styrene.
- A copolymer is indeed made from two or more different monomer units, and BUNA-S is correctly identified as such.
- **Conclusion:** This statement is true.

5. **Final Evaluation:**
- Since all four statements have been evaluated and found to be true, we need to identify if there is a statement that is not true based on the context of polymers discussed.
- If the question implies that one of the statements is incorrect, we must look for any misinterpretation or misrepresentation in the definitions or properties discussed.

### Conclusion:
Based on the analysis, all statements provided in the question appear to be true according to the information presented in the video transcript. Therefore, if one must choose a statement that is not true, it would be necessary to have additional context or statements that contradict the established facts.