Which one of the following has the minimum boiling point ?

Options

A. Isobutane
B. 1-Butyne
C. 1-Butene
D. n-Butane

Explanation

To determine which compound has the minimum boiling point among the given options (isobutane, 1-butyne, 1-butene, and n-butane), we can analyze the boiling points based on the types of compounds and their structures.

### Step-by-Step Solution:

1. **Identify the Compounds**:
- Isobutane (C4H10): A branched alkane.
- 1-Butyne (C4H6): An alkyne.
- 1-Butene (C4H8): An alkene.
- n-Butane (C4H10): A straight-chain alkane.

2. **Understand the Types of Compounds**:
- Alkanes (like isobutane and n-butane) generally have lower boiling points compared to alkenes and alkynes with the same number of carbon atoms due to their weaker van der Waals forces.
- Alkenes (like 1-butene) have slightly higher boiling points than alkanes because of the presence of a double bond, which increases the polarity and intermolecular forces.
- Alkynes (like 1-butyne) typically have higher boiling points than both alkenes and alkanes due to the presence of a triple bond, which further increases the strength of intermolecular forces.

3. **Compare the Boiling Points**:
- Among the alkanes, isobutane (branched) has a lower boiling point than n-butane (straight-chain) due to its compact structure.
- 1-Butene will have a higher boiling point than isobutane due to the presence of a double bond.
- 1-Butyne will have the highest boiling point among these compounds due to the triple bond.

4. **Conclusion**:
- Based on the analysis, isobutane has the minimum boiling point among the given options.

### Final Answer:
**Isobutane (Option A) has the minimum boiling point.**