Structure of `XeF_5-` and `XeO_3F_2` respectively are:

Options

A. Pentagonal planer,trigonal bipyramidal
B. Pentagonal planer, trigonal bipyramidal
C. Trigonal bipyramidal,pentagonal planer
D. Trigonal bipyramidal,trigonal bipyramidal

Answer

To determine the structures of `XeF5-` and `XeO3F2`, we will follow a systematic approach based on the concept of steric number and hybridization.

### Step 1: Determine the Steric Number for `XeF5-`

1. **Identify the central atom**: The central atom in `XeF5-` is xenon (Xe).
2. **Count the valence electrons**: Xenon has 8 valence electrons.
3. **Count the number of monovalent atoms**: There are 5 fluorine atoms (F), which are monovalent.
4. **Account for the charge**: The charge of the anion is -1.

Using the formula for steric number:
\[ \text{Steric Number} = \frac{1}{2} \left( \text{Number of valence electrons} + \text{Number of monovalent atoms} - \text{Charge of cation} + \text{Charge of anion} \right) \]
Substituting the values:
\[ \text{Steric Number} = \frac{1}{2} \left( 8 + 5 + 0 + 1 \right) = \frac{14}{2} = 7 \]

### Step 2: Determine the Hybridization and Geometry for `XeF5-`

1. **Identify hybridization**: For a steric number of 7, the hybridization is `sp^3d^3`.
2. **Determine the geometry**: The geometry corresponding to `sp^3d^3` is pentagonal bipyramidal.
3. **Determine the shape**: The presence of two lone pairs will result in a pentagonal planar shape.

### Step 3: Determine the Steric Number for `XeO3F2`

1. **Identify the central atom**: The central atom in `XeO3F2` is also xenon (Xe).
2. **Count the valence electrons**: Xenon has 8 valence electrons.
3. **Count the number of monovalent atoms**: There are 2 fluorine atoms (F) and 3 oxygen atoms (O), which are divalent.
4. **Account for the charge**: There is no charge on this molecule.

Using the formula for steric number:
\[ \text{Steric Number} = \frac{1}{2} \left( \text{Number of valence electrons} + \text{Number of monovalent atoms} - \text{Charge of cation} + \text{Charge of anion} \right) \]
Substituting the values:
\[ \text{Steric Number} = \frac{1}{2} \left( 8 + 5 + 0 + 0 \right) = \frac{13}{2} = 6.5 \]
However, we need to consider the actual number of bonding pairs and lone pairs. The correct approach is to count the total number of atoms bonded to Xe (5) and the lone pairs.

### Step 4: Determine the Hybridization and Geometry for `XeO3F2`

1. **Identify hybridization**: For a steric number of 5, the hybridization is `sp^3d`.
2. **Determine the geometry**: The geometry corresponding to `sp^3d` is trigonal bipyramidal.
3. **Determine the shape**: In this case, the more electronegative atoms (oxygen) will occupy the axial positions, while fluorine will occupy the equatorial positions.

### Final Structures

- **Structure of `XeF5-`**: Pentagonal planar shape with a pentagonal bipyramidal geometry.
- **Structure of `XeO3F2`**: Trigonal bipyramidal shape with trigonal bipyramidal geometry.