Which of the following hydrogen halide is liquid at 273K?

Options

A. HI
B. HBr
C. HCI
D. HF

Answer

To determine which hydrogen halide is liquid at 273 K (0 °C), we need to analyze the properties of the hydrogen halides: HF (hydrogen fluoride), HCl (hydrogen chloride), HBr (hydrogen bromide), and HI (hydrogen iodide).

### Step-by-Step Solution:

1. **Identify the Hydrogen Halides**: The hydrogen halides we are considering are HF, HCl, HBr, and HI.

2. **Understand the States of Matter at 273 K**: At 273 K (0 °C), we need to know which of these compounds can exist in a liquid state.

3. **Examine the Boiling Points**:
- **HF (Hydrogen Fluoride)**: Boiling point is approximately 19.5 °C.
- **HCl (Hydrogen Chloride)**: Boiling point is approximately -85 °C.
- **HBr (Hydrogen Bromide)**: Boiling point is approximately -66 °C.
- **HI (Hydrogen Iodide)**: Boiling point is approximately -35 °C.

4. **Determine Which is Liquid at 273 K**:
- HF has a boiling point of 19.5 °C, which means it will be in the liquid state at 0 °C (273 K).
- HCl, HBr, and HI have boiling points well below 0 °C, meaning they will be in gaseous form at this temperature.

5. **Conclusion**: The only hydrogen halide that is liquid at 273 K is HF (hydrogen fluoride).

### Final Answer:
**Hydrogen Fluoride (HF) is the hydrogen halide that is liquid at 273 K.**