Sulphate ion is isostructural with :

Options

A. `PO_(4)^(3-)`
B. `NO_(3)^(-)`
C. `CO_(3)^(2-)`
D. `NO_(2)^(-)`.

Answer

To determine which ion is isostructural with the sulfate ion (SO4²⁻), we need to analyze the structure and hybridization of the sulfate ion and compare it with the given options.

### Step 1: Analyze the Sulfate Ion (SO4²⁻)
- **Valence Electrons**: Sulfur (S) has 6 valence electrons. Each oxygen (O) has 6 valence electrons. The sulfate ion has a -2 charge, meaning we have 2 extra electrons.
- **Total Valence Electrons**: 6 (from S) + 4 × 6 (from 4 O) + 2 (for the -2 charge) = 32 valence electrons.
- **Structure**: Sulfur is the central atom bonded to four oxygen atoms. Two of the oxygen atoms will have a single bond (O⁻), and two will have double bonds (O=).
- **Hybridization**: The steric number is 4 (four sigma bonds, no lone pairs), which corresponds to sp³ hybridization.
- **Geometry**: The geometry is tetrahedral.

### Step 2: Compare with Given Options
1. **Option 1: PO4³⁻ (Phosphate Ion)**
- **Valence Electrons**: Phosphorus (P) has 5 valence electrons. The total for PO4³⁻ is 5 + 4 × 6 + 3 = 32 valence electrons.
- **Structure**: Phosphorus is the central atom bonded to four oxygen atoms, similar to sulfate.
- **Hybridization**: The steric number is 4 (four sigma bonds, no lone pairs), which corresponds to sp³ hybridization.
- **Geometry**: The geometry is tetrahedral.
- **Conclusion**: PO4³⁻ is isostructural with SO4²⁻.

2. **Option 2: NO3⁻ (Nitrate Ion)**
- **Valence Electrons**: Nitrogen (N) has 5 valence electrons. The total for NO3⁻ is 5 + 3 × 6 + 1 = 24 valence electrons.
- **Structure**: Nitrogen is bonded to three oxygen atoms.
- **Hybridization**: The steric number is 3 (three sigma bonds, no lone pairs), which corresponds to sp² hybridization.
- **Geometry**: The geometry is trigonal planar.
- **Conclusion**: NO3⁻ is not isostructural with SO4²⁻.

3. **Option 3: CO3²⁻ (Carbonate Ion)**
- **Valence Electrons**: Carbon (C) has 4 valence electrons. The total for CO3²⁻ is 4 + 3 × 6 + 2 = 26 valence electrons.
- **Structure**: Carbon is bonded to three oxygen atoms.
- **Hybridization**: The steric number is 3 (three sigma bonds, no lone pairs), which corresponds to sp² hybridization.
- **Geometry**: The geometry is trigonal planar.
- **Conclusion**: CO3²⁻ is not isostructural with SO4²⁻.

4. **Option 4: N2O2⁻ (Nitrite Ion)**
- **Valence Electrons**: Nitrogen has 5 valence electrons. The total for N2O2⁻ is 5 + 2 × 6 + 1 = 18 valence electrons.
- **Structure**: Nitrogen is bonded to two oxygen atoms.
- **Hybridization**: The steric number is 3 (two sigma bonds and one lone pair), which corresponds to sp² hybridization.
- **Geometry**: The geometry is bent.
- **Conclusion**: N2O2⁻ is not isostructural with SO4²⁻.

### Final Conclusion
The sulfate ion (SO4²⁻) is isostructural with the phosphate ion (PO4³⁻). Therefore, the answer is:

**Answer: PO4³⁻**