Which of the hexa -atomic species contains two lone pair on central atom and planar ?

Options

A. `XeF_(5)^(+)`
B. `XeF_(4)`
C. `XeF_(5)^(-)`
D. `XeF_(6)`

Explanation

To determine which hexa-atomic species contains two lone pairs on the central atom and is planar, we will analyze the given options step by step.

### Step 1: Understanding the term "hexa-atomic species"
A hexa-atomic species consists of six atoms. This means that the central atom must be bonded to five other atoms or have a total of six atoms in the molecular structure.

**Hint:** Remember that hexa-atomic means there are six atoms in total, including the central atom.

### Step 2: Analyzing the first option - XeF5⁺
1. **Valence Electrons Calculation:**
- Xenon (Xe) has 8 valence electrons.
- Fluorine (F) has 7 valence electrons, and there are 5 fluorine atoms.
- The positive charge indicates the loss of one electron.
- Total valence electrons = 8 (Xe) + 5 × 7 (F) - 1 (charge) = 8 + 35 - 1 = 42 electrons.
- Number of electron pairs = 42 / 2 = 21 pairs.

2. **Hybridization:**
- The hybridization can be calculated as follows:
- Number of bonding pairs = 5 (from 5 F atoms) and 1 lone pair (due to the positive charge).
- Total pairs = 5 + 1 = 6.
- Therefore, the hybridization is sp³d².

3. **Geometry:**
- The geometry of XeF5⁺ is octahedral.
- In octahedral geometry, the lone pair occupies one position, leading to a square pyramidal shape, which is not planar.

**Conclusion:** XeF5⁺ does not satisfy the criteria.

### Step 3: Analyzing the second option - XeF4
1. **Valence Electrons Calculation:**
- Total valence electrons = 8 (Xe) + 4 × 7 (F) = 8 + 28 = 36 electrons.
- Number of electron pairs = 36 / 2 = 18 pairs.

2. **Hybridization:**
- Number of bonding pairs = 4 (from 4 F atoms) and 2 lone pairs.
- Total pairs = 4 + 2 = 6.
- Therefore, the hybridization is sp³d².

3. **Geometry:**
- The geometry of XeF4 is square planar due to the presence of 2 lone pairs on the central atom.
- This structure is indeed planar.

**Conclusion:** XeF4 has 2 lone pairs and is planar, but it is not hexa-atomic (it is pentatomic).

### Step 4: Analyzing the third option - XeF5⁻
1. **Valence Electrons Calculation:**
- Total valence electrons = 8 (Xe) + 5 × 7 (F) + 1 (negative charge) = 8 + 35 + 1 = 44 electrons.
- Number of electron pairs = 44 / 2 = 22 pairs.

2. **Hybridization:**
- Number of bonding pairs = 5 (from 5 F atoms) and 2 lone pairs.
- Total pairs = 5 + 2 = 7.
- Therefore, the hybridization is sp³d³.

3. **Geometry:**
- The geometry of XeF5⁻ is pentagonal bipyramidal.
- The presence of 2 lone pairs makes the structure planar.

**Conclusion:** XeF5⁻ has 2 lone pairs and is planar, and it is hexa-atomic.

### Final Answer:
The hexa-atomic species that contains two lone pairs on the central atom and is planar is **XeF5⁻**.