What is incorrect regarding natural rubber?
1. It is cis polyisoprene
2. It is amorphous in nature
3. It has syndiotactic stereochemisty
4. Molecules of rubber have coiled conformation

Options

A. 1,2
B. 2,4
C. 1,2,3
D. 1,2,4

Answer

To determine which statement regarding natural rubber is incorrect, we will analyze each statement one by one.

### Step 1: Analyze Statement 1
**Statement 1: It is cis polyisoprene.**
- Natural rubber is primarily composed of polyisoprene, which is derived from the monomer isoprene. However, the term "cis polyisoprene" specifically refers to synthetic rubber. Natural rubber is simply polyisoprene, and it does not have the "cis" designation in its name.
- **Conclusion:** This statement is incorrect.

### Step 2: Analyze Statement 2
**Statement 2: It is amorphous in nature.**
- Natural rubber is known to have a crystalline structure when fully stretched. In its natural state, it exhibits both amorphous and crystalline characteristics, but it is primarily crystalline when stretched.
- **Conclusion:** This statement is also incorrect.

### Step 3: Analyze Statement 3
**Statement 3: It has syndiotactic stereochemistry.**
- Stereochemistry refers to the spatial arrangement of atoms in a molecule. Natural rubber, derived from isoprene, does not have syndiotactic stereochemistry; instead, it exhibits isotactic or atactic behavior. Syndiotactic refers to alternating arrangements, which is not applicable to natural rubber.
- **Conclusion:** This statement is incorrect.

### Step 4: Analyze Statement 4
**Statement 4: Molecules of rubber have coiled conformation.**
- Natural rubber molecules are long chains that can indeed coil due to their flexible structure. This coiling contributes to the rubber's elastic properties.
- **Conclusion:** This statement is correct.

### Final Conclusion
The incorrect statements regarding natural rubber are:
- Statement 1: It is cis polyisoprene.
- Statement 2: It is amorphous in nature.
- Statement 3: It has syndiotactic stereochemistry.

Thus, the answer to the question is that statements 1, 2, and 3 are incorrect.