According to VBT the extent of overlapping depends upon types of orbitals involved in overlapping and nature of overlapping. More will be the overlapping and the bond energy will also be high.
The incorrect order of bond dissociation energy will be :

Options

A. `H-H gt Cl - Cl gt Br - Br`
B. `Si - Si gt P- P gt Cl- Cl`
C. `C-C gt N -N gt O-O`
D. `H-Cl gt H- Br gt H -I`

Explanation

To determine the incorrect order of bond dissociation energy according to Valence Bond Theory (VBT), we need to analyze the bond types and their corresponding bond energies in the given options. Here’s a step-by-step solution:

### Step 1: Understand Bond Dissociation Energy
Bond dissociation energy is the energy required to break a bond between two atoms in a molecule. Generally, stronger bonds (shorter bond lengths) have higher bond dissociation energies, while weaker bonds (longer bond lengths) have lower bond dissociation energies.

**Hint:** Remember that shorter bonds are typically stronger and require more energy to break.

### Step 2: Analyze the Options
We will analyze each option to determine the correct order of bond dissociation energies.

#### Option A: H2, Cl2, Br2
- **H2**: Small atoms, short bond length, high bond dissociation energy.
- **Cl2**: Larger atoms than H, longer bond length, lower bond dissociation energy than H2.
- **Br2**: Even larger than Cl2, longer bond length, lower bond dissociation energy than Cl2.

**Order**: H2 > Cl2 > Br2 (This order is correct)

**Hint:** Compare the sizes of the atoms and their bond lengths.

#### Option B: Si-Si, P-P, Cl-Cl
- **Si-Si**: Single bond, requires moderate energy.
- **P-P**: Triple bond, requires high energy to break.
- **Cl-Cl**: Single bond, requires less energy than Si-Si.

**Order**: P-P > Si-Si > Cl-Cl (This order is incorrect because P-P should have the highest energy due to the triple bond.)

**Hint:** Remember that triple bonds require more energy to break than double or single bonds.

#### Option C: C-C, N-N, O=O
- **C-C**: Can form multiple bonds, strong bond, high energy.
- **N-N**: Triple bond, high energy required.
- **O=O**: Double bond, lower energy than N-N.

**Order**: C-C > N-N > O=O (This order is correct)

**Hint:** Consider the types of bonds formed between the atoms.

#### Option D: H-Cl, H-Br, H-I
- **H-Cl**: Strong bond, moderate energy.
- **H-Br**: Weaker bond than H-Cl, requires less energy.
- **H-I**: Weakest bond, requires the least energy.

**Order**: H-Cl > H-Br > H-I (This order is correct)

**Hint:** Look at the electronegativity and atomic size of the halogens.

### Step 3: Conclusion
After analyzing all the options, we find that the incorrect order of bond dissociation energy is in **Option B**: Si-Si, P-P, Cl-Cl.

**Final Answer: Option B is the incorrect order of bond dissociation energy.**