Assertion : In gaseous phase, `H_(2)O` and `H_(2)O_(2)` both have bent structures.
Reason Bond angle of both `H_(2)O` and `H_(2)O_(2)` is `104.5^(@)`.

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.

Explanation

To solve the given question, we need to analyze the assertion and reason provided regarding the structures and bond angles of H₂O (water) and H₂O₂ (hydrogen peroxide).

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that in the gaseous phase, both H₂O and H₂O₂ have bent structures.
- To evaluate this, we need to determine the molecular geometry of both compounds.

2. **Analyzing H₂O (Water)**:
- The molecular structure of H₂O consists of one oxygen atom bonded to two hydrogen atoms.
- Oxygen has two lone pairs of electrons and two bond pairs (from the hydrogen atoms).
- The hybridization of oxygen in H₂O is sp³ (4 regions of electron density: 2 lone pairs + 2 bond pairs).
- The ideal bond angle for a tetrahedral arrangement (sp³) is 109.5°, but due to lone pair repulsion, the bond angle in H₂O is reduced to approximately 104.5°.
- Therefore, H₂O has a bent structure.

3. **Analyzing H₂O₂ (Hydrogen Peroxide)**:
- The structure of H₂O₂ consists of two oxygen atoms connected by a single bond, with each oxygen bonded to one hydrogen atom.
- In the gaseous phase, H₂O₂ has a non-planar (open book) structure.
- The bond angle in H₂O₂ is approximately 94.8° in the gaseous phase, which is different from 104.5°.
- Therefore, H₂O₂ does not have a bent structure in the same sense as H₂O.

4. **Evaluating the Reason**:
- The reason states that the bond angle of both H₂O and H₂O₂ is 104.5°.
- This is incorrect because while H₂O has a bond angle of 104.5°, H₂O₂ has a bond angle of approximately 94.8° in the gaseous phase.

5. **Conclusion**:
- Since the assertion is incorrect (H₂O₂ does not have a bent structure) and the reason is also incorrect (the bond angle of H₂O₂ is not 104.5°), both the assertion and reason are false.

### Final Answer:
Both the assertion and reason are false.