Fluorine, the first member of group 17, differs form the other members of group in may respects due to:
i. Very small size
ii. Very high electronegativity
iii. Absence of vacant d-orbitals in the valence shell
iv. Dissociation energy in the molecular form `(X_(2))` is the least
Which of the following do not exist ?

Options

A. `IF`
B. `FCl_(3)`
C. `IF_(3)`
D. `IF_(5)`

Explanation

To solve the question regarding the existence of interhalogen compounds involving fluorine, we will analyze each option based on the properties of the halogens and the rules governing interhalogen compounds.

### Step-by-Step Solution:

1. **Understanding Interhalogen Compounds**:
Interhalogen compounds are formed from two different halogens. The general formula is \(XY_n\), where \(X\) is the less electronegative halogen and \(Y\) is the more electronegative halogen. The value of \(n\) can be 1, 3, 5, or 7.

2. **Analyzing Each Option**:
- **Option 1: IF**
- Iodine (I) is less electronegative than Fluorine (F). Thus, IF exists.
- **Option 2: FCl3**
- Fluorine (F) is more electronegative than Chlorine (Cl). Therefore, FCl3 cannot exist as it does not follow the rule that \(X\) must be less electronegative than \(Y\).
- **Option 3: IF3**
- Iodine (I) is less electronegative than Fluorine (F). Thus, IF3 exists.
- **Option 4: IF5**
- Iodine (I) is less electronegative than Fluorine (F). Thus, IF5 exists.

3. **Conclusion**:
From the analysis, the only compound that does not exist is **FCl3**. Therefore, the correct answer is **Option 2**.

### Final Answer:
**Option 2: FCl3 does not exist.**

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