Hydrocarbon which is liquid at room temperature is

Options

A. pentane
B. butane
C. propane
D. ethane

Explanation

To determine which hydrocarbon is liquid at room temperature from the given options (pentane, butane, propane, ethane), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Hydrocarbons**:
- **Pentane**: 5 carbon atoms (C5H12)
- **Butane**: 4 carbon atoms (C4H10)
- **Propane**: 3 carbon atoms (C3H8)
- **Ethane**: 2 carbon atoms (C2H6)

2. **Understand the State of Hydrocarbons at Room Temperature**:
- Generally, hydrocarbons with up to 4 carbon atoms are gases at room temperature.
- Hydrocarbons with more than 4 carbon atoms tend to be liquids at room temperature.

3. **Analyze Each Option**:
- **Pentane (C5H12)**: Has 5 carbon atoms, which means it is likely to be a liquid at room temperature.
- **Butane (C4H10)**: Has 4 carbon atoms, which means it is a gas at room temperature.
- **Propane (C3H8)**: Has 3 carbon atoms, which means it is a gas at room temperature.
- **Ethane (C2H6)**: Has 2 carbon atoms, which means it is a gas at room temperature.

4. **Conclusion**:
- Among the given options, only **pentane** has more than 4 carbon atoms and is therefore a liquid at room temperature.

### Final Answer:
The hydrocarbon which is liquid at room temperature is **pentane**.

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