Which of the following is a normal liquid

Options

A. `NH_3`
B. `H_2O`
C. `HF`
D. `Br_2`

Explanation

To determine which of the following substances is a normal liquid, we need to analyze the physical states of the given substances at room temperature (around 20°C). A normal liquid is one that exists in the liquid state under standard atmospheric pressure and temperature conditions without any special requirements.

### Step-by-Step Solution:

1. **Identify the substances**: The question mentions several substances, including water (H2O), hydrogen fluoride (HF), ammonia (NH3), and bromine (Br2).

2. **Analyze the state of each substance at room temperature**:
- **Water (H2O)**: Water is a liquid at room temperature due to hydrogen bonding. Its boiling point is 100°C.
- **Hydrogen Fluoride (HF)**: HF is also a liquid at room temperature, but it has a boiling point of about 19.5°C. It exists as a liquid under normal conditions.
- **Ammonia (NH3)**: Ammonia has a boiling point of -33°C, which means it is a gas at room temperature and does not exist as a liquid under normal conditions.
- **Bromine (Br2)**: Bromine is a reddish-brown liquid at room temperature, with a boiling point of 58.8°C. It exists as a liquid under normal conditions.

3. **Determine which substance is a normal liquid**:
- Both water (H2O) and hydrogen fluoride (HF) are liquids at room temperature, but they are special cases due to hydrogen bonding.
- Ammonia (NH3) is not a liquid at room temperature.
- Bromine (Br2) is a normal liquid at room temperature without any special conditions.

4. **Conclusion**: The substance that qualifies as a normal liquid is **Bromine (Br2)**.

### Final Answer:
**Bromine (Br2) is a normal liquid.**