In which of the following species presence of lone pair does not affect idealized bond angle ?
`(I) PF_(3) (II) BrF_(3) (III) IF_(5) (IV) I Cl_(4)^(-) (V) XeF_(2)`

Options

A. I,II,III
B. IV,V
C. II, V
D. None of these

Answer

To determine which of the given species has a lone pair that does not affect the idealized bond angle, we will analyze each molecule one by one, focusing on the presence of lone pairs and their impact on bond angles.

### Step-by-Step Solution:

1. **PF₃ (Phosphorus Trifluoride)**:
- **Structure**: PF₃ has one lone pair on phosphorus and three fluorine atoms bonded to it.
- **Effect of Lone Pair**: The lone pair will repel the bond pairs, leading to a distortion in the bond angles from the ideal tetrahedral angle (109.5°).
- **Conclusion**: The presence of the lone pair affects the bond angle. **Not our answer**.

2. **BrF₃ (Bromine Trifluoride)**:
- **Structure**: BrF₃ has three fluorine atoms bonded to bromine and two lone pairs on bromine.
- **Effect of Lone Pair**: The two lone pairs will exert repulsion on the bond pairs, causing a change in the bond angles from the ideal angles.
- **Conclusion**: The presence of the lone pairs affects the bond angle. **Not our answer**.

3. **IF₅ (Iodine Pentafluoride)**:
- **Structure**: IF₅ has five fluorine atoms bonded to iodine and one lone pair on iodine.
- **Effect of Lone Pair**: The lone pair will also repel the bond pairs, leading to a change in the bond angles.
- **Conclusion**: The presence of the lone pair affects the bond angle. **Not our answer**.

4. **ICl₄⁻ (Iodine Tetrachloride Ion)**:
- **Structure**: ICl₄⁻ has four chlorine atoms bonded to iodine and two lone pairs on iodine.
- **Effect of Lone Pair**: The two lone pairs are positioned opposite each other (axial positions), which minimizes their repulsion. This results in a net effect of zero on the bond angles.
- **Conclusion**: The lone pairs do not affect the bond angle. **This is one of our answers**.

5. **XeF₂ (Xenon Difluoride)**:
- **Structure**: XeF₂ has two fluorine atoms bonded to xenon and three lone pairs on xenon.
- **Effect of Lone Pair**: The three lone pairs are arranged in a trigonal bipyramidal geometry, with the bond pairs in the equatorial positions. The lone pairs will repel the bond pairs but will not distort the bond angles significantly.
- **Conclusion**: The lone pairs do not affect the bond angle. **This is another answer**.

### Final Answer:
The species in which the presence of lone pairs does not affect the idealized bond angle are:
- **ICl₄⁻**
- **XeF₂**