A bulb containing `N_(2)O_(4)` is colourless in ice. Its colour inboiling water is `………….` while in water at 298 K, it is ` ………… .`

Answer

To solve the question regarding the color of dinitrogen tetroxide (N₂O₄) at different temperatures, we will analyze the behavior of N₂O₄ in various states.

### Step-by-Step Solution:

1. **Understanding N₂O₄ Behavior**:
- N₂O₄ is a colorless gas at lower temperatures. When it is cooled (like in ice), it remains colorless.

2. **Color in Boiling Water**:
- When N₂O₄ is heated, it partially dissociates into nitrogen dioxide (NO₂), which is a brown gas.
- At boiling water temperature (100°C or 373 K), the equilibrium shifts towards NO₂, resulting in a reddish-brown color.

**Color in boiling water**: Reddish brown.

3. **Color at 298 K (25°C)**:
- At room temperature (298 K), N₂O₄ is still in equilibrium with NO₂, but the concentration of NO₂ is less compared to boiling water.
- This results in a pale brown color due to the presence of some NO₂, but not as intense as at boiling temperature.

**Color at 298 K**: Pale brown.

### Final Answer:
- Color in boiling water: **Reddish brown**
- Color at 298 K: **Pale brown**

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