When boron trifluoride forms an adduct with ammonia, what are the changes in the hybridisation and geometry ?

Explanation

To solve the question regarding the changes in hybridization and geometry when boron trifluoride (BF3) forms an adduct with ammonia (NH3), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Hybridization of BF3 and NH3 Before Reaction**:
- Boron trifluoride (BF3) has boron at the center. Boron has three valence electrons and forms three bonds with fluorine atoms. This results in an **sp² hybridization** for boron, leading to a **trigonal planar geometry**.
- Ammonia (NH3) has nitrogen at the center, which has five valence electrons. It forms three bonds with hydrogen and has one lone pair. This results in **sp³ hybridization** for nitrogen, leading to a **trigonal pyramidal geometry**.

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