Which of the following pairs of compound is isoelectronic and isostructure ?

Options

A. `BeCl_(2),XeF_(2)`
B. `Tel_(2), XeF_(2)`
C. `Ibr_(2)^(-), XeF_(2)`
D. `IF_(3), XeF_(2)`

Explanation

To determine which of the given pairs of compounds are isoelectronic and isostructural, we need to follow these steps:

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

### Step 2: Identify the Valence Electrons
We need to calculate the total number of valence electrons for each compound.

1. **BeCl2 (Beryllium Chloride)**:
- Beryllium (Be) has 2 valence electrons.
- Chlorine (Cl) has 7 valence electrons, and there are 2 Cl atoms.
- Total = 2 (Be) + 2 × 7 (Cl) = 2 + 14 = **16 valence electrons**.

2. **XeF2 (Xenon Difluoride)**:
- Xenon (Xe) has 8 valence electrons.
- Fluorine (F) has 7 valence electrons, and there are 2 F atoms.
- Total = 8 (Xe) + 2 × 7 (F) = 8 + 14 = **22 valence electrons**.

3. **TeI2 (Tellurium Iodide)**:
- Tellurium (Te) has 6 valence electrons.
- Iodine (I) has 7 valence electrons, and there are 2 I atoms.
- Total = 6 (Te) + 2 × 7 (I) = 6 + 14 = **20 valence electrons**.

4. **IBr2- (Iodine Bromide Ion)**:
- Iodine (I) has 7 valence electrons.
- Bromine (Br) has 7 valence electrons, and there are 2 Br atoms.
- The negative charge (-1) indicates one extra electron.
- Total = 7 (I) + 2 × 7 (Br) + 1 = 7 + 14 + 1 = **22 valence electrons**.

5. **IF3 (Iodine Trifluoride)**:
- Iodine (I) has 7 valence electrons.
- Fluorine (F) has 7 valence electrons, and there are 3 F atoms.
- Total = 7 (I) + 3 × 7 (F) = 7 + 21 = **28 valence electrons**.

### Step 3: Compare Valence Electrons
Now we compare the total number of valence electrons for each compound:
- BeCl2: 16
- XeF2: 22
- TeI2: 20
- IBr2-: 22
- IF3: 28

### Step 4: Identify Isoelectronic Pairs
From the calculations:
- **IBr2-** and **XeF2** both have **22 valence electrons**. Hence, they are isoelectronic.

### Step 5: Check for Isostructural Pairs
Now we need to check the geometry:
- **IBr2-**: Linear structure (due to 2 bonding pairs and 3 lone pairs).
- **XeF2**: Also has a linear structure (due to 3 lone pairs and 2 bonding pairs).

### Conclusion
The pair of compounds that are both isoelectronic and isostructural is **IBr2- and XeF2**.

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