Arrange the following compounds in increasing order of boiling point :
Prpane-1-ol, butan-1-ol, butan-2-ol, pentan-1-ol

Options

A. Propan-1-ol, butan-2-ol, butan-1-ol, pentan-1-ol
B. Propan-1-ol, butan-1-ol, butan-2-ol, pentan-1-ol
C. Pentan-1-ol, butan-2-ol, butan-1-ol, propan-1-ol
D. Pentan-1-ol, butan-1-ol, butan-2-ol, propan-1-ol

Explanation

To arrange the compounds propane-1-ol, butan-1-ol, butan-2-ol, and pentan-1-ol in increasing order of boiling point, we can follow these steps:

### Step 1: Understand the Factors Affecting Boiling Point
The boiling point of alcohols is influenced primarily by two factors:
1. **Molecular Mass**: Generally, as the molecular mass increases, the boiling point also increases.
2. **Structure of Alcohols**: Among isomeric alcohols (same molecular formula but different structures), the boiling point decreases in the order of primary > secondary > tertiary. This is due to the differences in surface area and hydrogen bonding.

### Step 2: Determine the Molecular Mass of Each Compound
- **Propane-1-ol (C3H8O)**: Molecular mass = 3(12) + 8(1) + 16 = 60 g/mol
- **Butan-1-ol (C4H10O)**: Molecular mass = 4(12) + 10(1) + 16 = 74 g/mol
- **Butan-2-ol (C4H10O)**: Molecular mass = 4(12) + 10(1) + 16 = 74 g/mol (same as butan-1-ol)
- **Pentan-1-ol (C5H12O)**: Molecular mass = 5(12) + 12(1) + 16 = 88 g/mol

### Step 3: Compare the Boiling Points Based on Molecular Mass
From the molecular masses calculated:
- Propane-1-ol: 60 g/mol
- Butan-1-ol: 74 g/mol
- Butan-2-ol: 74 g/mol
- Pentan-1-ol: 88 g/mol

Based on molecular mass alone, we can initially rank them as:
1. Propane-1-ol (60 g/mol)
2. Butan-1-ol (74 g/mol)
3. Butan-2-ol (74 g/mol)
4. Pentan-1-ol (88 g/mol)

### Step 4: Consider the Structure of Isomeric Alcohols
Since butan-1-ol and butan-2-ol have the same molecular mass, we need to consider their structure:
- **Butan-1-ol** is a primary alcohol.
- **Butan-2-ol** is a secondary alcohol.

According to the boiling point trend for isomeric alcohols (primary > secondary), butan-1-ol will have a higher boiling point than butan-2-ol.

### Step 5: Final Arrangement of Compounds
Now, we can arrange the compounds in increasing order of boiling point:
1. Propane-1-ol (lowest boiling point)
2. Butan-2-ol
3. Butan-1-ol
4. Pentan-1-ol (highest boiling point)

### Final Answer
The increasing order of boiling points is:
**Propane-1-ol < Butan-2-ol < Butan-1-ol < Pentan-1-ol**