The compound with the highest boiling point is:

Options

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

Answer

To determine which compound has the highest boiling point among the given options, we will analyze each compound based on factors that influence boiling points.

### Step-by-Step Solution:

1. **Understanding Boiling Point**:
- The boiling point is the temperature at which the vapor pressure of a liquid equals the external pressure surrounding the liquid. At this point, the liquid and vapor states exist in equilibrium.

2. **Identifying the Compounds**:
- The options given are:
- Ethanol (an alcohol)
- Ether (general formula ROH)
- Alkane (hydrocarbon)
- Aldehyde (RCHO)

3. **Factors Affecting Boiling Point**:
- Boiling points are influenced by molecular mass, chain size, and the presence of intermolecular forces such as hydrogen bonding.

4. **Analyzing Each Compound**:
- **Ethanol (C2H5OH)**:
- Ethanol has an -OH (hydroxyl) group, which allows for strong intermolecular hydrogen bonding. This significantly raises its boiling point.
- **Ether (R-O-R)**:
- Ethers have lower boiling points compared to alcohols of similar molecular weight because they do not engage in hydrogen bonding as effectively as alcohols.
- **Alkane (C_nH_(2n+2))**:
- Alkanes are non-polar and do not form hydrogen bonds. Their boiling points are generally lower than those of alcohols and ethers.
- **Aldehyde (RCHO)**:
- Aldehydes can engage in dipole-dipole interactions, but they do not form hydrogen bonds as strongly as alcohols.

5. **Conclusion**:
- Among the compounds analyzed, ethanol has the highest boiling point due to the presence of strong intermolecular hydrogen bonds. Therefore, the correct answer is:
- **Ethanol (Option 1)** has the highest boiling point.

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

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