How many optically active stereoisomers are possible for lactic acid ?

Options

A. 1
B. 2
C. 4
D. 3

Explanation

To determine how many optically active stereoisomers are possible for lactic acid, we can follow these steps:

### Step 1: Understand the Structure of Lactic Acid
Lactic acid has the molecular formula C3H6O3. The structure can be represented as:
- A central carbon atom (C) connected to:
- A hydroxyl group (OH)
- A methyl group (CH3)
- A hydrogen atom (H)
- A carboxyl group (COOH)

### Step 2: Identify Chiral Centers
A chiral center is a carbon atom that is bonded to four different groups. In lactic acid, we analyze the carbon atoms:
- The first carbon (attached to CH3) has three hydrogens and is not chiral.
- The second carbon (attached to OH, H, CH3, and COOH) has four different groups and is chiral.
- The third carbon (part of the carboxyl group) is also not chiral since it is part of a double bond.

Thus, there is **only one chiral center** in lactic acid.

### Step 3: Calculate the Number of Optically Active Stereoisomers
The formula to calculate the number of optically active stereoisomers is given by:
\[ \text{Number of stereoisomers} = 2^n \]
where \( n \) is the number of chiral centers.

Since we have identified that there is **1 chiral center** in lactic acid:
\[ \text{Number of stereoisomers} = 2^1 = 2 \]

### Conclusion
Therefore, lactic acid can have **2 optically active stereoisomers**.

### Final Answer
The number of optically active stereoisomers possible for lactic acid is **2**.

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