Highest boiling point is of :

Options

A. Ethanol
B. Ether
C. Alkane
D. Aldehyde

Answer

To determine which compound has the highest boiling point among ethanol, ether, alkane, and aldehyde, we need to analyze the intermolecular forces present in each type of compound.

### Step-by-Step Solution:

1. **Identify the Compounds**:
- Ethanol (C2H5OH)
- Ether (general structure ROR, e.g., dimethyl ether CH3OCH3)
- Alkane (e.g., methane CH4)
- Aldehyde (e.g., formaldehyde HCHO)

2. **Understand Intermolecular Forces**:
- **Ethanol**: Contains hydroxyl (-OH) group which allows for hydrogen bonding. Hydrogen bonds are strong intermolecular forces, leading to a higher boiling point.
- **Ether**: Contains an oxygen atom in the middle of two alkyl groups (ROR). Ethers can engage in dipole-dipole interactions but do not form hydrogen bonds as strongly as alcohols do.
- **Alkane**: Composed of carbon and hydrogen only (e.g., CH4). Alkanes primarily exhibit London dispersion forces, which are the weakest intermolecular forces.
- **Aldehyde**: Contains a carbonyl group (C=O). Aldehydes can exhibit dipole-dipole interactions but do not engage in hydrogen bonding as effectively as alcohols.

3. **Compare Boiling Points**:
- **Ethanol**: Due to strong hydrogen bonding, ethanol has a significantly higher boiling point compared to ethers, alkanes, and aldehydes.
- **Ether**: Lower boiling point than ethanol due to weaker dipole-dipole interactions.
- **Alkane**: Lowest boiling point due to only having London dispersion forces.
- **Aldehyde**: Higher boiling point than alkane but lower than ethanol due to dipole-dipole interactions.

4. **Conclusion**:
- Among the given compounds, ethanol has the highest boiling point due to the presence of strong hydrogen bonding.

### Final Answer:
**Ethanol has the highest boiling point.**