The compound which has the lowest boiling points is

Options

A. `H_(2)O`
B. `C_(2)H_(5)OH`
C. `underset(OH)underset(|)CH_(2)-underset(OH)underset(|)CH_(2)`
D. `CH_(3)OCH_(3)`

Answer

To determine which compound has the lowest boiling point, we can follow these steps:

### Step 1: Understand the Factors Affecting Boiling Point
Boiling point is influenced by several factors, including molecular mass and the presence of intermolecular forces such as hydrogen bonding. Generally, compounds with stronger intermolecular forces have higher boiling points.

**Hint:** Remember that hydrogen bonding significantly increases boiling points compared to compounds that do not exhibit this type of bonding.

### Step 2: Identify the Compounds
The compounds mentioned are:
1. Water (H2O)
2. Ethanol (C2H5OH)
3. Diol (a compound with two hydroxyl groups, e.g., CH2(OH)CH2(OH))
4. Ether (e.g., CH3OCH3)

**Hint:** List the compounds clearly to analyze their structures and bonding.

### Step 3: Analyze Each Compound for Hydrogen Bonding
- **Water (H2O)**: Exhibits strong hydrogen bonding due to the presence of two hydrogen atoms bonded to oxygen.
- **Ethanol (C2H5OH)**: Also exhibits hydrogen bonding due to the hydroxyl (OH) group.
- **Diol**: Has two hydroxyl groups, which means it can form even more hydrogen bonds than ethanol.
- **Ether (e.g., CH3OCH3)**: Lacks an -OH group, resulting in negligible hydrogen bonding.

**Hint:** Identify which compounds can form hydrogen bonds and how many they can form.

### Step 4: Compare Boiling Points
- **Water**: High boiling point (100°C) due to strong hydrogen bonding.
- **Ethanol**: Lower boiling point than water but still significant due to hydrogen bonding.
- **Diol**: Expected to have a higher boiling point than both water and ethanol due to increased hydrogen bonding.
- **Ether**: Expected to have the lowest boiling point because it does not exhibit hydrogen bonding.

**Hint:** Recall that the more hydrogen bonds present, the higher the boiling point.

### Step 5: Conclusion
Based on the analysis, the compound with the lowest boiling point is the **ether**, as it lacks hydrogen bonding and therefore requires less thermal energy to boil.

**Final Answer:** The compound which has the lowest boiling point is **ether**.