Arrange the following species in increasing order of bond angle
`NF_(3), NCl_(3) , NBr_(3) , NI_(3)`

Options

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

Answer

To arrange the species NF₃, NCl₃, NBr₃, and NI₃ in increasing order of bond angle, we can follow these steps:

### Step 1: Understand the Molecular Geometry
All four species have a similar molecular geometry due to the presence of one lone pair of electrons on nitrogen. The molecular shape is trigonal pyramidal for each of them.

### Step 2: Identify the Electronegativity of Halogens
The bond angle in these molecules is influenced by the electronegativity of the halogens attached to nitrogen. The electronegativity decreases in the order:
- Fluorine (F) > Chlorine (Cl) > Bromine (Br) > Iodine (I)

### Step 3: Analyze the Effect of Electronegativity on Bond Angles
- **NF₃**: Fluorine is the most electronegative, which means it pulls the bonding electrons closer to itself. This results in less electron crowding around the nitrogen atom, leading to a smaller bond angle.
- **NCl₃**: Chlorine is less electronegative than fluorine, so there is slightly more electron crowding around nitrogen compared to NF₃, resulting in a larger bond angle than NF₃.
- **NBr₃**: Bromine is even less electronegative than chlorine, causing further increase in electron crowding around nitrogen, leading to a larger bond angle than NCl₃.
- **NI₃**: Iodine is the least electronegative of the group, which means it has the least tendency to attract the bonding electrons. This results in the greatest electron crowding around nitrogen, leading to the largest bond angle.

### Step 4: Arrange the Species Based on Bond Angles
Based on the analysis of electronegativity and its effect on electron crowding, we can arrange the species in increasing order of bond angle as follows:
1. NF₃ (smallest bond angle)
2. NCl₃
3. NBr₃
4. NI₃ (largest bond angle)

### Final Order
Thus, the increasing order of bond angles is:
**NF₃ < NCl₃ < NBr₃ < NI₃**