Which of the following compound is achiral ( optically inactive )?

Options

A. 1− Bromo−2−chlorocyclopropane
B. (Trans)−2−Methyl hex−3−ene
C. 2− Methyl butanal
D. 2,2,4− Trimethyl hexane

Explanation

To determine which of the given compounds is achiral (optically inactive), we will analyze each option step by step.

### Step 1: Analyze Option A - 1-bromo-2-chloro-cyclopropane
1. **Structure**: The compound consists of a cyclopropane ring with a bromine (Br) and a chlorine (Cl) substituent.
2. **Chirality Check**: A chiral center is a carbon atom that is attached to four different groups. In this case, the carbon atoms in the cyclopropane ring with Br and Cl attached can create two different configurations.
3. **Conclusion**: Since there are two chiral centers, this compound is optically active.

### Step 2: Analyze Option B - trans-2-methyl-hex-3-ene
1. **Structure**: The compound has a double bond between two carbon atoms and two methyl groups on the second carbon.
2. **Chirality Check**: For a compound to be chiral, it must have at least one carbon atom bonded to four different substituents. In this case, the carbons involved in the double bond do not have four different groups attached.
3. **Conclusion**: This compound does not have any chiral centers, making it optically inactive.

### Step 3: Analyze Option C - 2-methylbutanol
1. **Structure**: The compound has a butanol structure with a methyl group on the second carbon.
2. **Chirality Check**: The second carbon is bonded to four different groups (a hydroxyl group, a methyl group, and two different carbon chains).
3. **Conclusion**: This compound has a chiral center, making it optically active.

### Step 4: Analyze Option D - 2,2,4-trimethylhexane
1. **Structure**: The compound has a hexane backbone with three methyl groups.
2. **Chirality Check**: The carbon at position 2 is bonded to two identical methyl groups, which means it does not have four different substituents.
3. **Conclusion**: This compound does not have a chiral center, making it optically inactive.

### Final Conclusion:
The only compound that is achiral (optically inactive) is **Option B - trans-2-methyl-hex-3-ene**.