The X - X bond dissociation energy is minimum in:

Options

A. (A) `F_2`
B. (B) `Cl_2`
C. (C) `Br_2`
D. (D)`l_2`

Answer

To determine which X-X bond dissociation energy is minimum among F2, Cl2, Br2, and I2, we can follow these steps:

### Step 1: Understand Bond Dissociation Energy
Bond dissociation energy is the energy required to break a bond between two atoms in a molecule. A lower bond dissociation energy indicates that the bond is weaker and easier to break.

### Step 2: Analyze the Halogens
The halogens in question are:
- F2 (Fluorine)
- Cl2 (Chlorine)
- Br2 (Bromine)
- I2 (Iodine)

As we move down the group in the periodic table from fluorine to iodine, the size of the atoms increases due to the addition of electron shells.

### Step 3: Consider Bond Length
Bond length increases as the size of the atoms increases. A longer bond length typically results in a weaker bond because the atoms are further apart, making it easier to break the bond.

### Step 4: Compare the Bond Lengths
- F2 has a shorter bond length due to the small size of fluorine atoms.
- Cl2 has a longer bond length than F2 but shorter than Br2.
- Br2 has a longer bond length than Cl2 but shorter than I2.
- I2 has the longest bond length due to the larger size of iodine atoms.

### Step 5: Evaluate Bond Dissociation Energies
- F2 has a relatively high bond dissociation energy, but due to lone pair repulsion, it is lower than expected.
- Cl2 has a higher bond dissociation energy than F2.
- Br2 has a higher bond dissociation energy than Cl2.
- I2 has the lowest bond dissociation energy because it has the longest bond length, making it the weakest bond.

### Conclusion
The bond dissociation energy is minimum in I2.

### Final Answer
The X - X bond dissociation energy is minimum in I2.

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