In which of the following bond angle can not be explained by Valence Bond Theory?

Options

A. `H_(2)O`
B. `H_(2)Po`
C. `H_(2)S`
D. `H_(2)Te`

Answer

To determine which bond angle cannot be explained by Valence Bond Theory (VBT), we need to analyze the bond angles in different molecules and how they relate to the hybridization of the central atom.

### Step-by-Step Solution:

1. **Understanding Valence Bond Theory (VBT)**:
- VBT explains that bonds are formed through the overlap of atomic orbitals, which can be hybridized to form new orbitals. The geometry and bond angles are determined by the type of hybridization.

2. **Analyzing the Molecules**:
- We will consider the bond angles in H2O (water), H2S (hydrogen sulfide), H2Te (hydrogen telluride), and H2 (hydrogen gas).

3. **H2O (Water)**:
- The central atom is oxygen (O), which is sp³ hybridized.
- The ideal bond angle for sp³ hybridization is 109.5 degrees. However, due to the presence of two lone pairs on oxygen, the bond angle is reduced to approximately 104.5 degrees due to lone pair-lone pair and lone pair-bond pair repulsion.

4. **H2S (Hydrogen Sulfide)**:
- The central atom is sulfur (S), which is also sp³ hybridized.
- The bond angle is slightly less than 109.5 degrees but is not significantly distorted compared to water because sulfur is larger and has less lone pair repulsion.

5. **H2Te (Hydrogen Telluride)**:
- The central atom is tellurium (Te), which is similarly sp³ hybridized.
- The bond angle is again close to 109.5 degrees but is less affected by lone pair repulsion due to the larger size of tellurium.

6. **H2 (Hydrogen Gas)**:
- In H2, there is no central atom with hybridization affecting bond angles since it is a diatomic molecule with a single bond. The bond angle is not applicable here.

7. **Conclusion**:
- The bond angle in H2O cannot be fully explained by VBT due to the significant distortion caused by lone pairs. In contrast, the bond angles in H2S and H2Te can be explained by VBT, albeit with some minor deviations due to size and repulsion effects. H2 does not have a bond angle to consider.

### Final Answer:
The bond angle that cannot be explained by Valence Bond Theory is that of **H2O (water)** due to the significant influence of lone pair repulsion.