The strongest bond among these is :

Options

A. `F-F`
B. `Cl-Cl`
C. `Br-Br`
D. `I-I`

Answer

To determine the strongest bond among the given options, we need to analyze the bonds formed by the halogens: fluorine (F), chlorine (Cl), bromine (Br), and iodine (I).

### Step-by-Step Solution:

1. **Identify the Bonds**: The bonds in question are F-F, Cl-Cl, Br-Br, and I-I. These are all covalent bonds formed between the same type of atoms.

2. **Understand Bond Strength**: The strength of a bond can be influenced by factors such as bond length, atomic size, and electron repulsion. Generally, shorter bonds are stronger due to the closer proximity of the nuclei, which leads to a stronger attraction between them.

3. **Analyze F-F Bond**:
- The F-F bond is relatively weak. This is mainly due to the small size of the fluorine atom, which leads to significant lone pair-lone pair repulsion between the two fluorine atoms.
- Additionally, the bond length in F-F is longer compared to other halogens, making it weaker.

4. **Analyze Cl-Cl Bond**:
- The Cl-Cl bond is stronger than the F-F bond. Chlorine atoms are larger than fluorine atoms, which results in less lone pair repulsion compared to the F-F bond.
- The bond length in Cl-Cl is shorter than that in F-F, contributing to its strength.

5. **Analyze Br-Br and I-I Bonds**:
- The Br-Br bond is weaker than Cl-Cl but stronger than F-F due to increasing atomic size and bond length.
- The I-I bond is the weakest among these bonds due to the largest atomic size and the longest bond length.

6. **Conclusion**:
- Among the bonds analyzed, the Cl-Cl bond is the strongest due to its shorter bond length and lesser repulsion compared to the F-F bond.
- Therefore, the strongest bond among the options given is the Cl-Cl bond.

### Final Answer:
The strongest bond among the given options is the **Cl-Cl bond**.