Which of the following pairs of ions are isoelectronic and isostructural ?

Options

A. `SO_3^(2-), NO_3^(-)`
B. `ClO_3^(-), SO_3^(2-)`
C. `ClO_3^(-) , CO_3^(2-)`
D. `CO_3^(2-) ,NO_3^(-)`

Explanation

To determine which pairs of ions are isoelectronic and isostructural, we need to analyze the given options step by step.

### Step 1: Understand Isoelectronic and Isostructural
- **Isoelectronic ions** are ions that have the same number of electrons.
- **Isostructural ions** are ions that have the same structure or geometry.

### Step 2: Analyze Each Option
We will analyze each option to check if they are isoelectronic and isostructural.

#### Option 1:
- **Ions:** \( \text{SO}_3^{2-} \) and \( \text{NO}_3^{-} \)
- **Calculating Electrons:**
- For \( \text{SO}_3^{2-} \): Sulfur (16) + 3×Oxygen (8) + 2 (charge) = 16 + 24 + 2 = 42 electrons.
- For \( \text{NO}_3^{-} \): Nitrogen (7) + 3×Oxygen (8) + 1 (charge) = 7 + 24 + 1 = 32 electrons.
- **Conclusion:** Not isoelectronic.

#### Option 2:
- **Ions:** \( \text{ClO}_3^{-} \) and \( \text{SO}_3^{2-} \)
- **Calculating Electrons:**
- For \( \text{ClO}_3^{-} \): Chlorine (17) + 3×Oxygen (8) + 1 (charge) = 17 + 24 + 1 = 42 electrons.
- For \( \text{SO}_3^{2-} \): Already calculated as 42 electrons.
- **Conclusion:** Isoelectronic.

- **Checking Structure:**
- Both have a tetrahedral geometry (sp³ hybridization).
- **Conclusion:** Isoelectronic and isostructural.

#### Option 3:
- **Ions:** \( \text{ClO}_3^{-} \) and \( \text{CO}_3^{2-} \)
- **Calculating Electrons:**
- For \( \text{ClO}_3^{-} \): Already calculated as 42 electrons.
- For \( \text{CO}_3^{2-} \): Carbon (6) + 3×Oxygen (8) + 2 (charge) = 6 + 24 + 2 = 32 electrons.
- **Conclusion:** Not isoelectronic.

#### Option 4:
- **Ions:** \( \text{ClO}_3^{2-} \) and \( \text{NO}_3^{-} \)
- **Calculating Electrons:**
- For \( \text{ClO}_3^{2-} \): Chlorine (17) + 3×Oxygen (8) + 2 (charge) = 17 + 24 + 2 = 43 electrons.
- For \( \text{NO}_3^{-} \): Already calculated as 32 electrons.
- **Conclusion:** Not isoelectronic.

### Final Conclusion
From the analysis, the only pair that is both isoelectronic and isostructural is:
- **Option 2: \( \text{ClO}_3^{-} \) and \( \text{SO}_3^{2-} \)**