Which of the following elements have `+3` as most popular oxidation state?

Options

A. `Al`
B. `Xe`
C. `Cu`
D. `Sc`

Answer

To determine which of the elements have +3 as the most popular oxidation state, we will analyze the given elements: aluminium, xenon, copper, and scandium.

### Step-by-Step Solution:

1. **Identify the Elements and Their Groups**:
- Aluminium (Al) is in Group 13 (p-block).
- Xenon (Xe) is in Group 18 (noble gases).
- Copper (Cu) is in Group 11 (d-block).
- Scandium (Sc) is in Group 3 (d-block).

2. **Determine the Electronic Configurations**:
- Aluminium: [Ne] 3s² 3p¹
- Xenon: [Kr] 4s² 4p⁶
- Copper: [Ar] 4s¹ 3d¹⁰
- Scandium: [Ar] 4s² 3d¹

3. **Analyze Oxidation States**:
- **Aluminium (Al)**: The most common oxidation states are +3 and +1. However, +3 is the most stable due to the loss of three valence electrons (2 from 3s and 1 from 3p).
- **Xenon (Xe)**: As a noble gas, xenon typically has an oxidation state of 0.
- **Copper (Cu)**: The most common oxidation states are +1 and +2. It does not commonly exhibit +3 oxidation state.
- **Scandium (Sc)**: The common oxidation states are +2 and +3. The +3 state is stable as it loses all three valence electrons (2 from 4s and 1 from 3d).

4. **Conclusion**:
- The elements that have +3 as the most popular oxidation state are Aluminium (Al) and Scandium (Sc).

### Final Answer:
The elements that have +3 as the most popular oxidation state are **Aluminium (Al)** and **Scandium (Sc)**.