Count the no. of ions which can form low spin & high spin complexes when co-ordination no. 6 `Co^(+3),Ni^(2+)Cr^(+3),Fe^(+2),Fe^(+3),Cu^(+2),Ti^(+3),Co^(+2)`

Explanation

To determine the number of ions that can form both low spin and high spin complexes when the coordination number is 6, we will analyze each ion based on its electronic configuration and the ability to pair electrons in the presence of a strong field ligand.

### Step-by-Step Solution:

1. **Cobalt (Co³⁺)**:
- Electronic configuration: [Ar] 3d⁶
- Co³⁺ has the capacity to pair electrons. Therefore, it can form both low spin and high spin complexes.
- **Result**: Both high spin and low spin complexes are possible.

2. **Nickel (Ni²⁺)**:
- Electronic configuration: [Ar] 3d⁸
- Ni²⁺ has a low pairing capacity as it is already more than half-filled. Therefore, it will only form high spin complexes.
- **Result**: Only high spin complexes are possible.

3. **Chromium (Cr³⁺)**:
- Electronic configuration: [Ar] 3d³
- Cr³⁺ has the capacity to pair electrons, allowing it to form both low spin and high spin complexes.
- **Result**: Both high spin and low spin complexes are possible.

4. **Iron (Fe²⁺)**:
- Electronic configuration: [Ar] 3d⁶
- Fe²⁺ can also pair electrons, thus it can form both low spin and high spin complexes.
- **Result**: Both high spin and low spin complexes are possible.

5. **Iron (Fe³⁺)**:
- Electronic configuration: [Ar] 3d⁵
- Fe³⁺ has a fully half-filled d-orbital and can pair electrons, allowing for both low spin and high spin complexes.
- **Result**: Both high spin and low spin complexes are possible.

6. **Copper (Cu²⁺)**:
- Electronic configuration: [Ar] 3d⁹
- Cu²⁺ is more than half-filled and has a low pairing capacity, thus it can only form high spin complexes.
- **Result**: Only high spin complexes are possible.

7. **Titanium (Ti³⁺)**:
- Electronic configuration: [Ar] 3d²
- Ti³⁺ has the capacity to pair electrons, allowing it to form both low spin and high spin complexes.
- **Result**: Both high spin and low spin complexes are possible.

8. **Cobalt (Co²⁺)**:
- Electronic configuration: [Ar] 3d⁷
- Co²⁺ is more than half-filled and has a low pairing capacity, thus it can only form high spin complexes.
- **Result**: Only high spin complexes are possible.

### Summary of Results:
- Ions that can form both low spin and high spin complexes: Co³⁺, Cr³⁺, Fe²⁺, Fe³⁺, Ti³⁺ (Total: 5 ions)
- Ions that can only form high spin complexes: Ni²⁺, Cu²⁺, Co²⁺ (Total: 3 ions)

### Final Answer:
The number of ions that can form both low spin and high spin complexes is **5**.