Number of optically active isomers of tartaric acid is –
`underset(CH(OH)COOH) underset(| ) (C H (OH ) COOH`

Options

A. 2
B. 3
C. 4
D. 5

Answer

To determine the number of optically active isomers of tartaric acid, we can follow these steps:

### Step 1: Understand the Structure of Tartaric Acid
Tartaric acid has the molecular formula C4H6O6 and contains two chiral centers. Its structure can be represented as follows:

```
HOOC
|
HO-C-H
|
HO-C-H
|
HOOC
```

### Step 2: Identify Chiral Centers
In tartaric acid, the two carbon atoms that are bonded to hydroxyl (OH) groups are chiral centers. A chiral center is a carbon atom that is attached to four different groups.

### Step 3: Determine Possible Isomers
Since there are two chiral centers, the total number of stereoisomers can be calculated using the formula \(2^n\), where \(n\) is the number of chiral centers.

For tartaric acid:
- \(n = 2\)
- Total stereoisomers = \(2^2 = 4\)

### Step 4: Identify Optically Active Isomers
Among the four stereoisomers, we need to determine which ones are optically active. An optically active compound is one that does not have a plane of symmetry.

1. **Meso Compound**: One of the isomers of tartaric acid is a meso compound, which has a plane of symmetry and is not optically active.
2. **Chiral Isomers**: The other two isomers are chiral and do not have a plane of symmetry, making them optically active.

### Step 5: Count the Optically Active Isomers
Thus, out of the four stereoisomers:
- 1 is a meso compound (not optically active)
- 2 are optically active

### Conclusion
The number of optically active isomers of tartaric acid is **2**.

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