Which of the following are not isoelectronic speices ?

Options

A. `PO_(4)^(3-),SO_(4)^(2-),CIO_(4)^(Theta)`
B. `SO_(3)^(2-),CO_(3)^(2-),NO_(3)^(Theta)`
C. `BO_(3)^(3-),CO_(3)^(2-),NO_(3)^(Theta)`
D. `CN^(Theta),N_(2),C_(2)^(2-)`

Explanation

To determine which of the following species are not isoelectronic, we need to calculate the total number of electrons for each species. Isoelectronic species have the same number of electrons. Let's analyze the given options step by step.

### Step 1: Calculate the total number of electrons for each species in the first set.

1. **PO4^3-**:
- Phosphorus (P) has 15 electrons.
- Each Oxygen (O) has 8 electrons, and there are 4 O atoms: 4 × 8 = 32 electrons.
- The charge of -3 means we add 3 electrons.
- Total = 15 + 32 + 3 = **50 electrons**.

2. **SO4^2-**:
- Sulfur (S) has 16 electrons.
- Each Oxygen (O) has 8 electrons, and there are 4 O atoms: 4 × 8 = 32 electrons.
- The charge of -2 means we add 2 electrons.
- Total = 16 + 32 + 2 = **50 electrons**.

3. **ClO4^-**:
- Chlorine (Cl) has 17 electrons.
- Each Oxygen (O) has 8 electrons, and there are 4 O atoms: 4 × 8 = 32 electrons.
- The charge of -1 means we add 1 electron.
- Total = 17 + 32 + 1 = **50 electrons**.

**Conclusion for Step 1**: PO4^3-, SO4^2-, and ClO4^- are isoelectronic (all have 50 electrons).

### Step 2: Calculate the total number of electrons for each species in the second set.

1. **SO3^2-**:
- Sulfur (S) has 16 electrons.
- Each Oxygen (O) has 8 electrons, and there are 3 O atoms: 3 × 8 = 24 electrons.
- The charge of -2 means we add 2 electrons.
- Total = 16 + 24 + 2 = **42 electrons**.

2. **CO3^2-**:
- Carbon (C) has 6 electrons.
- Each Oxygen (O) has 8 electrons, and there are 3 O atoms: 3 × 8 = 24 electrons.
- The charge of -2 means we add 2 electrons.
- Total = 6 + 24 + 2 = **32 electrons**.

3. **NO3^-**:
- Nitrogen (N) has 7 electrons.
- Each Oxygen (O) has 8 electrons, and there are 3 O atoms: 3 × 8 = 24 electrons.
- The charge of -1 means we add 1 electron.
- Total = 7 + 24 + 1 = **32 electrons**.

**Conclusion for Step 2**: SO3^2- has 42 electrons, while CO3^2- and NO3^- both have 32 electrons. Therefore, these species are not isoelectronic.

### Step 3: Calculate the total number of electrons for each species in the third set.

1. **BO3^3-**:
- Boron (B) has 5 electrons.
- Each Oxygen (O) has 8 electrons, and there are 3 O atoms: 3 × 8 = 24 electrons.
- The charge of -3 means we add 3 electrons.
- Total = 5 + 24 + 3 = **32 electrons**.

2. **CO3^2-**:
- As calculated before, CO3^2- has **32 electrons**.

3. **NO3^-**:
- As calculated before, NO3^- has **32 electrons**.

**Conclusion for Step 3**: BO3^3-, CO3^2-, and NO3^- are isoelectronic (all have 32 electrons).

### Step 4: Calculate the total number of electrons for each species in the last set.

1. **CN^-**:
- Carbon (C) has 6 electrons.
- Nitrogen (N) has 7 electrons.
- The charge of -1 means we add 1 electron.
- Total = 6 + 7 + 1 = **14 electrons**.

2. **N2**:
- Each Nitrogen (N) has 7 electrons, and there are 2 N atoms.
- Total = 7 + 7 = **14 electrons**.

3. **C2^2-**:
- Each Carbon (C) has 6 electrons, and there are 2 C atoms: 2 × 6 = 12 electrons.
- The charge of -2 means we add 2 electrons.
- Total = 12 + 2 = **14 electrons**.

**Conclusion for Step 4**: CN^-, N2, and C2^2- are isoelectronic (all have 14 electrons).

### Final Conclusion:
From our calculations, the only set of species that are not isoelectronic is from the second set: SO3^2-, CO3^2-, and NO3^-.

### Summary:
The species that are **not isoelectronic** are **SO3^2-**.