Arrange the following compounds in decreasing order of their boiling points
(i) `CH_(3)Cl`
(ii) `CH_(3)CH_(2)Cl`
(iii) `CH_(3)CH_(2)CH_(2)Cl`
(iv) `CH_(3)CH_(2)CH_(2)CH_(2)Cl`

Options

A. `(iii) gt(iv) gt (i) gt (ii)`
B. `(iv) gt (iii) gt (ii) gt (i)`
C. `(i) gt (iii) gt (ii) gt (iv)`
D. `(i) gt (ii) gt (iii) gt (iv)`

Answer

To arrange the compounds `CH₃Cl`, `CH₃CH₂Cl`, `CH₃CH₂CH₂Cl`, and `CH₃CH₂CH₂CH₂Cl` in decreasing order of their boiling points, we will follow these steps:

### Step 1: Identify the Compounds
The compounds are:
1. `CH₃Cl` (Methyl chloride)
2. `CH₃CH₂Cl` (Ethyl chloride)
3. `CH₃CH₂CH₂Cl` (Propyl chloride)
4. `CH₃CH₂CH₂CH₂Cl` (Butyl chloride)

### Step 2: Consider the Factors Affecting Boiling Points
The boiling point of a compound is influenced by:
- Molecular weight
- Type of substituents (in this case, they all have Cl)
- Branching (none of these compounds are branched)

### Step 3: Analyze Molecular Weights
The molecular weights of the compounds can be calculated as follows:
- `CH₃Cl`: 12 (C) + 3 (H) + 35.5 (Cl) = 50.5 g/mol
- `CH₃CH₂Cl`: 12 (C) + 2*1 (H) + 12 (C) + 35.5 (Cl) = 64.5 g/mol
- `CH₃CH₂CH₂Cl`: 12 (C) + 3*1 (H) + 12 (C) + 12 (C) + 35.5 (Cl) = 78.5 g/mol
- `CH₃CH₂CH₂CH₂Cl`: 12 (C) + 4*1 (H) + 12 (C) + 12 (C) + 35.5 (Cl) = 92.5 g/mol

### Step 4: Compare the Molecular Weights
From the calculations above, we can see that:
- `CH₃Cl` has the lowest molecular weight (50.5 g/mol)
- `CH₃CH₂Cl` has a higher molecular weight (64.5 g/mol)
- `CH₃CH₂CH₂Cl` has an even higher molecular weight (78.5 g/mol)
- `CH₃CH₂CH₂CH₂Cl` has the highest molecular weight (92.5 g/mol)

### Step 5: Arrange in Decreasing Order of Boiling Points
Since molecular weight is a significant factor affecting boiling points, we can arrange the compounds in decreasing order of their boiling points based on their molecular weights:
1. `CH₃CH₂CH₂CH₂Cl` (Butyl chloride) - highest boiling point
2. `CH₃CH₂CH₂Cl` (Propyl chloride)
3. `CH₃CH₂Cl` (Ethyl chloride)
4. `CH₃Cl` (Methyl chloride) - lowest boiling point

### Final Answer
The order of the compounds in decreasing order of their boiling points is:
`CH₃CH₂CH₂CH₂Cl` > `CH₃CH₂CH₂Cl` > `CH₃CH₂Cl` > `CH₃Cl`