Among the given pairs in which pair, first compound has higher boiling point than second ?

Options

A. `CH_3 - CH_2 OCH_3 and CH_3-underset(OH)underset(|)(CH)-CH_3`
B. `CH_3 - CH_2 -CH_2-CH_3and CH_3-CH_2-CH_3`
C. `CH_3 - CH_2 -CH_2-CH_2-CH_3 and CH_3-overset(CH_2-CH_3)overset(|)(CH)-CH_2-OH`
D. `CH_3 - CH_2-CH_2-CH_3 and CH_3-CH_2-CH_2-Cl`

Explanation

To determine which pair of compounds has the first compound with a higher boiling point than the second, we need to analyze the boiling points of the compounds based on several factors such as hydrogen bonding, surface area, and dipole moment.

### Step-by-Step Solution:

1. **Understanding Boiling Point Factors**:
- Boiling point is influenced by:
- **Hydrogen bonding**: More hydrogen bonds lead to higher boiling points.
- **Surface area**: Larger surface area generally results in higher boiling points due to increased van der Waals forces.
- **Dipole moment**: Greater polarity can lead to higher boiling points.

2. **Analyzing the Given Pairs**:
- **Pair 1**: CH3CH2OCH3 (ether) vs. CH3CH2OH (alcohol)
- The alcohol can form hydrogen bonds, while the ether cannot. Thus, CH3CH2OH has a higher boiling point.

- **Pair 2**: CH3CH2CH2CH3 (butane) vs. CH3CH2CH3 (propane)
- Butane has a larger surface area than propane, leading to a higher boiling point. Therefore, CH3CH2CH2CH3 has a higher boiling point.

- **Pair 3**: CH3CH2OH (ethanol) vs. CH3CH(CH3)OH (isopropanol)
- Both compounds can form hydrogen bonds, but isopropanol has a branched structure which generally lowers the boiling point compared to straight-chain alcohols. Thus, CH3CH2OH has a higher boiling point.

- **Pair 4**: CH3CH2CH2CH3 (butane) vs. CH3CH2CH3 (propane)
- Similar to Pair 2, butane has a larger surface area than propane, leading to a higher boiling point. Therefore, CH3CH2CH2CH3 has a higher boiling point.

3. **Conclusion**:
- The pairs where the first compound has a higher boiling point than the second are:
- Pair 2: CH3CH2CH2CH3 > CH3CH2CH3
- Pair 4: CH3CH2CH2CH3 > CH3CH2CH3

### Final Answer:
The pairs in which the first compound has a higher boiling point than the second are:
- Pair 2: CH3CH2CH2CH3 (butane) > CH3CH2CH3 (propane)
- Pair 4: CH3CH2CH2CH3 (butane) > CH3CH2CH3 (propane)