The element that usually does NOT show variable oxidation states is :

Options

A. `Cu`
B. `Ti`
C. `Sc`
D. `V`

Answer

To determine which element does not show variable oxidation states among copper, titanium, scandium, and vanadium, we can analyze the electronic configurations and possible oxidation states of each element.

### Step-by-step Solution:

1. **Identify the Elements and Their Atomic Numbers:**
- Copper (Cu) - Atomic Number: 29
- Titanium (Ti) - Atomic Number: 22
- Scandium (Sc) - Atomic Number: 21
- Vanadium (V) - Atomic Number: 23

2. **Write the Electronic Configurations:**
- **Copper (Cu):**
- Electronic Configuration: [Ar] 3d¹⁰ 4s¹
- Possible Oxidation States: +1 (losing 4s electron) and +2 (losing one 3d electron).
- **Titanium (Ti):**
- Electronic Configuration: [Ar] 3d² 4s²
- Possible Oxidation States: +2 (losing 4s electrons) and +4 (losing both 4s and 3d electrons).
- **Scandium (Sc):**
- Electronic Configuration: [Ar] 3d¹ 4s²
- Possible Oxidation State: +3 (losing 4s and 3d electrons). Scandium predominantly exhibits only this oxidation state.
- **Vanadium (V):**
- Electronic Configuration: [Ar] 3d³ 4s²
- Possible Oxidation States: +2 (losing 4s electrons), +3 (losing 3d and 4s), +4, and +5 (losing all 5 electrons).

3. **Analyze the Oxidation States:**
- Copper shows variable oxidation states: +1 and +2.
- Titanium shows variable oxidation states: +2 and +4.
- Scandium predominantly shows only one oxidation state: +3.
- Vanadium shows variable oxidation states: +2, +3, +4, and +5.

4. **Conclusion:**
- The element that usually does NOT show variable oxidation states is **Scandium (Sc)**, as it primarily exhibits only the +3 oxidation state.

### Final Answer:
**Scandium (Sc)** is the element that does not show variable oxidation states.

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