Consider the following species: `CF_(4),GeH_(4),BCl_(3),AlBr_(3),H_(2)O,PH_(3),PCl_(5),CO_(2),CH_(4) and ` calculate value of `(x-y)^(2)`:
Where, x: Total number of species which can act as only lewis acid.
y: total number of species which can act as lewis acid as well as lewis base.

Explanation

To solve the problem, we need to classify the given species into two categories: those that can act only as Lewis acids and those that can act as both Lewis acids and Lewis bases.

### Step-by-Step Solution:

1. **Identify the Species**: We have the following species to consider:
- CF₄
- GeH₄
- BCl₃
- AlBr₃
- H₂O
- PH₃
- PCl₅
- CO₂
- CH₄

2. **Determine Lewis Acids**: A Lewis acid is a species that can accept a pair of electrons. We will check each species:
- **CF₄**: Cannot accept electrons (no vacant orbitals). Not a Lewis acid.
- **GeH₄**: Can accept electrons (has vacant orbitals). Lewis acid.
- **BCl₃**: Can accept electrons (has vacant orbitals). Lewis acid.
- **AlBr₃**: Can accept electrons (has vacant orbitals). Lewis acid.
- **H₂O**: Cannot accept electrons (but can donate). Not a Lewis acid.
- **PH₃**: Cannot accept electrons (but can donate). Not a Lewis acid.
- **PCl₅**: Can accept electrons (has vacant orbitals). Lewis acid.
- **CO₂**: Can accept electrons (due to polarization). Lewis acid.
- **CH₄**: Cannot accept electrons (no vacant orbitals). Not a Lewis acid.

**Total Lewis Acids (x)**: GeH₄, BCl₃, AlBr₃, PCl₅, CO₂ → 5 species.

3. **Determine Lewis Bases**: A Lewis base is a species that can donate a pair of electrons. We will check each species:
- **CF₄**: No lone pairs. Not a Lewis base.
- **GeH₄**: No lone pairs. Not a Lewis base.
- **BCl₃**: No lone pairs. Not a Lewis base.
- **AlBr₃**: No lone pairs. Not a Lewis base.
- **H₂O**: Has lone pairs (can donate). Lewis base.
- **PH₃**: Has lone pairs (can donate). Lewis base.
- **PCl₅**: No lone pairs. Not a Lewis base.
- **CO₂**: No lone pairs. Not a Lewis base.
- **CH₄**: No lone pairs. Not a Lewis base.

**Total Lewis Bases (y)**: H₂O, PH₃ → 2 species.

4. **Calculate (x - y)²**:
- x = 5 (Lewis acids)
- y = 2 (Lewis bases)
- (x - y)² = (5 - 2)² = 3² = 9.

### Final Answer:
The value of (x - y)² is **9**.