Which of the following is optically active

Options

A.
B.
C.
D. All of these

Answer

To determine which of the given compounds is optically active, we need to identify if they possess chiral centers. A chiral center is typically a carbon atom that is attached to four different substituents. Here’s a step-by-step analysis:

### Step 1: Understand the Concept of Chirality
- Chirality refers to the property of a molecule that makes it non-superimposable on its mirror image. A compound is considered optically active if it has at least one chiral center.

**Hint:** Look for carbon atoms that are bonded to four different groups.

### Step 2: Analyze Compound 1
- Draw the structure of Compound 1. Identify the carbon atoms and their substituents.
- Check for a carbon atom that has four different substituents. In this case, one carbon has:
- CH3 (methyl group)
- A double bond (which can be considered as a different group)
- Another CH3
- A hydrogen atom
- Since this carbon has four different groups, it is a chiral center.

**Hint:** Count the different groups attached to each carbon.

### Step 3: Analyze Compound 2
- Draw the structure of Compound 2 and identify the carbon atoms.
- Look for a carbon atom that has four different substituents. Here, you can find:
- One hydrogen
- A CH2 group
- Another CH2 group
- A different substituent
- This carbon also has four different groups, making it a chiral center.

**Hint:** Check for symmetry; if a carbon has two identical groups, it cannot be chiral.

### Step 4: Analyze Compound 3
- Draw the structure of Compound 3 and identify the carbon atoms.
- Look for carbon atoms with four different substituents. In this compound:
- One carbon has CH3, C2H5, and two hydrogens.
- This carbon also qualifies as a chiral center.

**Hint:** Remember that having two identical substituents means the carbon is not chiral.

### Step 5: Conclusion
- Since all three compounds have at least one chiral center, they are all optically active.
- Therefore, the answer is that all of the compounds listed are optically active.

**Final Answer:** All of the above compounds are optically active.