Which of the following is least basic?

Options

A. `NF_(3)`
B. `NCl_(3)`
C. `NBr_(3)`
D. `NI_(3)`

Explanation

To determine which of the given nitrogen trihalides is the least basic, we will analyze the compounds based on their structure and the electronegativity of the halogen atoms involved.

### Step-by-Step Solution:

1. **Identify the Compounds**: The compounds given are:
- Option 1: Nitrogen trifluoride (NF3)
- Option 2: Nitrogen trichloride (NCl3)
- Option 3: Nitrogen tribromide (NBr3)
- Option 4: Nitrogen triiodide (NI3)

2. **Understand Basicity**: Basicity in this context refers to the ability of a compound to donate a lone pair of electrons. The more basic a compound is, the more readily it can donate its lone pair.

3. **Analyze Electronegativity**: The electronegativity of the halogens decreases as we move down the group in the periodic table:
- Fluorine (F) > Chlorine (Cl) > Bromine (Br) > Iodine (I)

4. **Effect of Electronegativity on Basicity**:
- In nitrogen trifluoride (NF3), fluorine is highly electronegative and pulls electron density away from nitrogen, making it less able to donate its lone pair.
- In nitrogen trichloride (NCl3), chlorine is less electronegative than fluorine, which means nitrogen retains more electron density and is more basic than NF3.
- In nitrogen tribromide (NBr3) and nitrogen triiodide (NI3), the trend continues with bromine and iodine being even less electronegative than chlorine, allowing nitrogen to be more basic in these compounds.

5. **Conclusion**: Since fluorine is the most electronegative halogen, nitrogen trifluoride (NF3) has the least ability to donate its lone pair of electrons, making it the least basic among the options provided.

### Final Answer:
The least basic compound is **Nitrogen trifluoride (NF3)**.

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