The number of optically inactive stereoisomers possible for tartaric acid.

Explanation

To determine the number of optically inactive stereoisomers possible for tartaric acid, follow these steps:

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

```
HOOC
|
C
/ \
OH H
|
C
/ \
H OH
```

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

### Step 3: Determine Stereoisomers
The number of stereoisomers can be calculated using the formula \(2^n\), where \(n\) is the number of chiral centers. For tartaric acid, \(n = 2\):

\[ \text{Number of stereoisomers} = 2^2 = 4 \]

### Step 4: Classify Stereoisomers
Out of the four stereoisomers, we can classify them into two types:
1. **Optically Active Stereoisomers**: These are the pairs of enantiomers that are non-superimposable mirror images of each other.
2. **Optically Inactive Stereoisomers**: These include meso compounds that have a plane of symmetry.

### Step 5: Identify the Meso Compound
Among the four stereoisomers of tartaric acid, one of them is a meso compound. A meso compound is achiral despite having chiral centers because it has an internal plane of symmetry.

### Step 6: Conclusion
Thus, the number of optically inactive stereoisomers (meso compounds) for tartaric acid is:

\[ \text{Number of optically inactive stereoisomers} = 1 \]

### Final Answer
The number of optically inactive stereoisomers possible for tartaric acid is **1**.

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