The correct order of boiling points is

Options

A. `CH_(3)F lt CH_(3)Cl lt CH_(3)Br lt CH_(3)I`
B. `CH_(3)F lt CH_(3)I lt CH_(3)Br lt CH_(3)Cl`
C. `CH_(3)I lt CH_(3)Br lt CH_(3)Cl lt CH_(3)F`
D. `CH_(3)F lt CH_(3)Br lt CH_(3)Cl lt CH_(3)I`

Answer

To determine the correct order of boiling points for haloalkanes, we need to consider the molecular weight of the halogens attached to the alkyl group, as well as the intermolecular forces present in these compounds. Here's a step-by-step solution:

### Step 1: Identify the Compounds
Let's assume we have the following haloalkanes:
- CH3I (Methyl iodide)
- CH3Br (Methyl bromide)
- CH3Cl (Methyl chloride)
- CH3F (Methyl fluoride)

### Step 2: Analyze the Halogens
The halogens attached to the alkyl group differ in their molecular weights. The order of molecular weights for the halogens is:
1. Iodine (I) - highest molecular weight
2. Bromine (Br)
3. Chlorine (Cl)
4. Fluorine (F) - lowest molecular weight

### Step 3: Relate Molecular Weight to Boiling Point
Boiling points are influenced by the strength of intermolecular forces, which are generally stronger in compounds with higher molecular weights. Therefore, the boiling point increases with increasing molecular weight.

### Step 4: Arrange the Compounds Based on Boiling Points
Given that the alkyl group (CH3) is the same in all cases, we can directly relate the boiling points to the molecular weights of the halogens:
- CH3I (Methyl iodide) will have the highest boiling point due to iodine's high molecular weight.
- CH3Br (Methyl bromide) will have a lower boiling point than CH3I but higher than CH3Cl.
- CH3Cl (Methyl chloride) will have a lower boiling point than CH3Br.
- CH3F (Methyl fluoride) will have the lowest boiling point due to fluorine's low molecular weight.

### Final Order of Boiling Points
Thus, the correct order of boiling points from highest to lowest is:
**CH3I > CH3Br > CH3Cl > CH3F**