In which of the following pairs, both the species are not isostructural?

Options

A. `SiCl_(4),PCl_(4)^(+)`
B. Diamond, carbide
C. `NH_(3), PH_(3)`
D. `XeF_(4), XeO_(4)`

Explanation

To determine which of the given pairs of species are not isostructural, we need to analyze the molecular geometry and hybridization of each species. Let's go through the pairs step by step.

### Step 1: Analyze SiCl4
- **Molecular Formula**: SiCl4
- **Central Atom**: Silicon (Si)
- **Geometry**: Tetrahedral
- **Hybridization**: sp³
- **Explanation**: Silicon is surrounded by four chlorine atoms, leading to a tetrahedral shape.

### Step 2: Analyze PCl4+
- **Molecular Formula**: PCl4+
- **Central Atom**: Phosphorus (P)
- **Geometry**: Tetrahedral
- **Hybridization**: sp³
- **Explanation**: Phosphorus is surrounded by four chlorine atoms and has a positive charge, but the geometry remains tetrahedral.

### Step 3: Analyze Diamond and Silicon Carbide (SiC)
- **Molecular Formula**: Diamond (C) and SiC
- **Central Atom**: Carbon in diamond and Silicon in SiC
- **Geometry**: Tetrahedral
- **Hybridization**: sp³
- **Explanation**: Both diamond and silicon carbide have a tetrahedral arrangement of atoms.

### Step 4: Analyze NH3 and PH3
- **Molecular Formula**: NH3 and PH3
- **Central Atom**: Nitrogen (N) in NH3 and Phosphorus (P) in PH3
- **Geometry**: Pyramidal
- **Hybridization**: sp³ for NH3 and sp³ for PH3
- **Explanation**: Both have a pyramidal shape due to the presence of a lone pair on the central atom.

### Step 5: Analyze XeF4
- **Molecular Formula**: XeF4
- **Central Atom**: Xenon (Xe)
- **Geometry**: Square planar
- **Hybridization**: sp³d²
- **Explanation**: Xenon is surrounded by four fluorine atoms and has two lone pairs, resulting in a square planar shape.

### Step 6: Analyze XeO4
- **Molecular Formula**: XeO4
- **Central Atom**: Xenon (Xe)
- **Geometry**: Tetrahedral
- **Hybridization**: sp³
- **Explanation**: Xenon is surrounded by four oxygen atoms, leading to a tetrahedral shape.

### Conclusion
- **Isostructural Pairs**:
- SiCl4 and PCl4+ (both tetrahedral)
- Diamond and SiC (both tetrahedral)
- NH3 and PH3 (both pyramidal)
- **Not Isostructural**:
- XeF4 (square planar) and XeO4 (tetrahedral)

Thus, the answer to the question is that **XeF4 and XeO4** are the pair that is not isostructural.

### Final Answer
The pair in which both species are not isostructural is **XeF4 and XeO4**.