To determine which pairs of ions are isoelectronic and isostructural, we will analyze each option step by step.
### Step 1: Understand the Definitions
- **Isoelectronic**: Ions or molecules that have the same number of electrons.
- **Isostructural**: Ions or molecules that have the same structure or geometry.
### Step 2: Analyze Each Pair of Ions
We will go through the given pairs one by one.
#### Pair 1: CO₃²⁻ and NO₃⁻
1. **Calculate the number of electrons**:
- For CO₃²⁻:
- Carbon (C) has 6 electrons.
- Each Oxygen (O) has 8 electrons, and there are 3 Oxygens: 3 × 8 = 24.
- Total = 6 + 24 + 2 (for the 2 negative charges) = 32 electrons.
- For NO₃⁻:
- Nitrogen (N) has 7 electrons.
- Each Oxygen (O) has 8 electrons, and there are 3 Oxygens: 3 × 8 = 24.
- Total = 7 + 24 + 1 (for the negative charge) = 32 electrons.
2. **Conclusion**: Both CO₃²⁻ and NO₃⁻ have 32 electrons, so they are isoelectronic.
3. **Determine the structure**:
- For CO₃²⁻, the hybridization is sp² (3 bond pairs, 0 lone pairs), resulting in a trigonal planar structure.
- For NO₃⁻, the hybridization is also sp² (3 bond pairs, 0 lone pairs), resulting in a trigonal planar structure.
4. **Conclusion**: CO₃²⁻ and NO₃⁻ are both isoelectronic and isostructural.
#### Pair 2: ClO₃⁻ and CO₃²⁻
1. **Calculate the number of electrons**:
- For CO₃²⁻, we already found it has 32 electrons.
- For ClO₃⁻:
- Chlorine (Cl) has 17 electrons.
- Each Oxygen (O) has 8 electrons, and there are 3 Oxygens: 3 × 8 = 24.
- Total = 17 + 24 + 1 (for the negative charge) = 42 electrons.
2. **Conclusion**: ClO₃⁻ has 42 electrons, while CO₃²⁻ has 32. They are not isoelectronic.
#### Pair 3: SO₃²⁻ and NO₃⁻
1. **Calculate the number of electrons**:
- For NO₃⁻, we already found it has 32 electrons.
- For SO₃²⁻:
- Sulfur (S) has 16 electrons.
- Each Oxygen (O) has 8 electrons, and there are 3 Oxygens: 3 × 8 = 24.
- Total = 16 + 24 + 2 (for the 2 negative charges) = 42 electrons.
2. **Conclusion**: SO₃²⁻ has 42 electrons, while NO₃⁻ has 32. They are not isoelectronic.
#### Pair 4: ClO₃⁻ and SO₃²⁻
1. **Calculate the number of electrons**:
- For ClO₃⁻, we found it has 42 electrons.
- For SO₃²⁻, we found it has 42 electrons.
2. **Conclusion**: Both ClO₃⁻ and SO₃²⁻ have 42 electrons, so they are isoelectronic.
3. **Determine the structure**:
- For ClO₃⁻, the hybridization is sp³ (3 bond pairs, 1 lone pair), resulting in a pyramidal structure.
- For SO₃²⁻, the hybridization is also sp³ (3 bond pairs, 1 lone pair), resulting in a pyramidal structure.
4. **Conclusion**: ClO₃⁻ and SO₃²⁻ are both isoelectronic and isostructural.
### Final Answer
The pairs that are isoelectronic and isostructural are:
- Pair 1: CO₃²⁻ and NO₃⁻
- Pair 4: ClO₃⁻ and SO₃²⁻
