Which of the following hydrides has the smallest bond angle?

Options

A. `H_2Se`
B. `H_2S`
C. `H_2Te`
D. `H_2O`

Explanation

To determine which hydride has the smallest bond angle, we need to analyze the bond angles of the hydrides of the elements in Group 16 of the periodic table: water (H₂O), hydrogen sulfide (H₂S), hydrogen selenide (H₂Se), and hydrogen telluride (H₂Te).

### Step-by-Step Solution:

1. **Identify the Hydrides**: The hydrides we are considering are H₂O (water), H₂S (hydrogen sulfide), H₂Se (hydrogen selenide), and H₂Te (hydrogen telluride).

2. **Understand the Molecular Geometry**:
- H₂O has a bent shape due to the two lone pairs on oxygen.
- H₂S also has a bent shape but with fewer lone pairs compared to H₂O.
- H₂Se and H₂Te follow the same trend.

3. **Consider the Size and Electronegativity**:
- As we move down the group from oxygen to tellurium, the size of the central atom increases.
- Larger atoms have more diffuse electron clouds, which can lead to decreased repulsion between bonding pairs.

4. **Analyze Bond Angles**:
- H₂O has a bond angle of approximately 104.5° due to significant lone pair-lone pair and lone pair-bond pair repulsions.
- H₂S has a bond angle of about 92° because the larger sulfur atom results in less repulsion between the bonding pairs compared to the lone pairs.
- H₂Se and H₂Te will have even smaller bond angles due to the increasing size of selenium and tellurium, which further reduces the repulsion between the bond pairs.

5. **Conclusion**:
- Among the hydrides, H₂Te will have the smallest bond angle due to the largest atomic size and the least amount of repulsion between the bonding pairs.
- Therefore, the hydride with the smallest bond angle is **H₂Te**.

### Final Answer:
The hydride with the smallest bond angle is **H₂Te**.