An alkane of molecular weight 86 g/mol on monochlorination gives two products. The alkane is

Options

A. 2 - Methylbutane
B. n - butane
C. 2, 2- Dimethyl propane
D. 2, 3- Dimethyl butane

Answer

To solve the problem of identifying the alkane with a molecular weight of 86 g/mol that yields two products upon monochlorination, we can follow these steps:

### Step 1: Determine the General Formula for Alkanes
The general formula for alkanes is given by:
\[ C_nH_{2n+2} \]
where \( n \) is the number of carbon atoms.

### Step 2: Set Up the Equation for Molecular Weight
Given that the molecular weight of the alkane is 86 g/mol, we can express this in terms of \( n \):
\[ 12n + (2n + 2) = 86 \]
Here, 12 is the atomic weight of carbon (C), and 1 is the atomic weight of hydrogen (H).

### Step 3: Simplify the Equation
Combine the terms in the equation:
\[ 12n + 2n + 2 = 86 \]
\[ 14n + 2 = 86 \]

### Step 4: Solve for \( n \)
Subtract 2 from both sides:
\[ 14n = 84 \]
Now, divide by 14:
\[ n = 6 \]

### Step 5: Write the Molecular Formula
Using the value of \( n \):
\[ C_6H_{2(6)+2} = C_6H_{14} \]

### Step 6: Identify Possible Alkanes
Now, we need to identify which alkane with the formula \( C_6H_{14} \) can yield two products upon monochlorination. The possible candidates are:
1. 2-methylbutane
2. n-hexane
3. 2,2-dimethylpentane
4. 2,3-dimethylpentane

### Step 7: Analyze Each Candidate
- **2-methylbutane (C6H14)**: This compound has a branched structure and can yield two different products upon monochlorination.
- **n-hexane (C6H14)**: This is a straight-chain alkane and will yield only one product upon monochlorination.
- **2,2-dimethylpentane (C6H14)**: This compound will also yield only one product upon monochlorination due to its symmetrical structure.
- **2,3-dimethylpentane (C6H14)**: This compound can yield two different products upon monochlorination.

### Step 8: Conclusion
The alkane that fits the criteria of having a molecular weight of 86 g/mol and yielding two products upon monochlorination is **2,3-dimethylpentane**.