All terpenes have carbon skeletons made up of:

Options

A. Isoprenes units
B. Vinyl units
C. Alkenes
D. Ethylene units

Answer

To solve the question "All terpenes have carbon skeletons made up of:", we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Terpenes**:
- Terpenes are organic compounds primarily produced by plants and some insects. They are significant components of essential oils.

2. **Identifying the Structure**:
- Terpenes are classified as hydrocarbons, meaning they are composed solely of carbon (C) and hydrogen (H) atoms.

3. **Isoprene Units**:
- The fundamental building blocks of terpenes are isoprene units. An isoprene unit has the molecular formula C5H8 and is characterized by a specific structure that includes a double bond.

4. **Classification of Terpenes**:
- Terpenes can be classified based on the number of isoprene units:
- **Hemiterpenes**: Contain one isoprene unit.
- **Monoterpenes**: Contain two isoprene units.
- Larger terpenes contain more isoprene units.

5. **Conclusion**:
- Since all terpenes are constructed from isoprene units, we can conclude that the carbon skeletons of terpenes are made up of isoprene units.

6. **Evaluating Options**:
- Given the options:
- Isoprene unit (Correct)
- Vinyl unit (Incorrect)
- Alkene (Incorrect)
- Ethylene unit (Incorrect)
- The correct answer is the first option: "isoprene unit".

### Final Answer:
All terpenes have carbon skeletons made up of **isoprene units**.

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