Assertion : bond angle H2O is less than the normal tetrahedral bond angle.
Reason : Lone pair-lone pair repulsion decreases bond angle.

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion.
B. If both assertion and reason are true but reason is not the correct explanation of assertion.
C. If assertion is true but reason is false.
D. If both assertion and reason are false.

Answer

To solve the question, we need to analyze both the assertion and the reason provided.

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that the bond angle in H2O (water) is less than the normal tetrahedral bond angle (which is approximately 109.5 degrees).
- In water, the bond angle is actually about 104.5 degrees.

2. **Understanding the Reason**:
- The reason given is that "lone pair-lone pair repulsion decreases bond angle."
- In the case of water, the oxygen atom has two lone pairs and forms two bonds with hydrogen atoms.

3. **Analyzing the Molecular Geometry**:
- The molecular geometry of water can be described as bent or V-shaped due to the presence of two lone pairs on the oxygen atom.
- The hybridization of the oxygen in water is sp3, which typically has a tetrahedral arrangement of electron pairs.

4. **Effect of Lone Pairs on Bond Angles**:
- In a tetrahedral arrangement, the ideal bond angle is 109.5 degrees. However, lone pairs occupy more space than bonding pairs, leading to greater repulsion.
- This increased repulsion from the lone pairs pushes the bonding pairs closer together, resulting in a smaller bond angle.

5. **Conclusion**:
- Since the bond angle in H2O is indeed less than the normal tetrahedral bond angle due to the presence of lone pairs, both the assertion and reason are correct.
- Furthermore, the reason provided correctly explains why the bond angle is less than the tetrahedral angle.

### Final Answer:
- Assertion: True
- Reason: True
- The reason is the correct explanation for the assertion.