Which molecular geometry is least likely to result from a trigonal bipyramidal electron geometry ?

Options

A. Trigonal planar
B. See-saw
C. Linear
D. T-shpaed

Explanation

To determine which molecular geometry is least likely to result from a trigonal bipyramidal (TBP) electron geometry, we need to analyze the options provided based on the steric number and hybridization.

### Step-by-Step Solution:

1. **Understanding Trigonal Bipyramidal Geometry**:
- Trigonal bipyramidal geometry corresponds to a steric number of 5. This means there are 5 regions of electron density around the central atom, which can be a combination of bond pairs and lone pairs.
- The hybridization associated with this geometry is sp³d.

2. **Analyzing the Options**:
- The options given are:
1. Trigonal planar
2. Seesaw
3. Linear
4. T-shaped

3. **Evaluating Each Option**:
- **Trigonal Planar**: This geometry has a steric number of 3 (3 bond pairs, no lone pairs). Since trigonal bipyramidal has a steric number of 5, trigonal planar cannot arise from it.
- **Seesaw**: This geometry can occur when there are 4 bond pairs and 1 lone pair (steric number 5). This is a valid molecular geometry for TBP.
- **Linear**: This geometry can occur when there are 2 bond pairs and 3 lone pairs (steric number 5). This is also a valid molecular geometry for TBP.
- **T-shaped**: This geometry can occur when there are 3 bond pairs and 2 lone pairs (steric number 5). This is also a valid molecular geometry for TBP.

4. **Conclusion**:
- Among the options, **trigonal planar** is the least likely molecular geometry to result from a trigonal bipyramidal electron geometry because it does not match the required steric number.

### Final Answer:
The molecular geometry least likely to result from a trigonal bipyramidal electron geometry is **trigonal planar**.