Account for the following :
The experimentally determined N_F bond length in ` NF_(3)` is greater than the sum of the sigle
covalent radii of N and F.

Explanation

To account for the observation that the experimentally determined N-F bond length in NF₃ is greater than the sum of the single covalent radii of nitrogen (N) and fluorine (F), we can analyze the factors influencing bond lengths in covalent compounds.

### Step-by-Step Solution:

1. **Understanding Covalent Radii**:
- Covalent radii are the measure of the size of an atom that forms part of a single covalent bond. The sum of the covalent radii of nitrogen and fluorine gives an estimate of the bond length if we assume that the atoms are spheres that touch each other.

2. **Experimental Bond Length**:
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