The incorrect statement about ribose is

Options

A. It is a polyhydroxy compound
B. It is an aldehyde sugar
C. It has six carbon atoms
D. It exhibits optical activity

Explanation

To determine the incorrect statement about ribose, we will analyze each option provided in the question.

### Step-by-Step Solution:

1. **Understanding Ribose Structure**:
- Ribose is a five-carbon sugar (pentose) with the molecular formula C5H10O5. It is a type of monosaccharide.

2. **Analyzing Each Statement**:
- **Option 1: "It is a polyhydroxyl compound."**
- Ribose contains multiple hydroxyl (–OH) groups. Therefore, this statement is **correct**.

- **Option 2: "It is an aldehydic sugar."**
- Ribose has an aldehyde group in its structure, which classifies it as an aldose sugar. Thus, this statement is also **correct**.

- **Option 3: "It has six carbon atoms."**
- Ribose has only five carbon atoms (C5), not six. Therefore, this statement is **incorrect**.

- **Option 4: "It exhibits optical activity."**
- Ribose has multiple chiral centers (specifically, it has four chiral centers), which allows it to exhibit optical isomerism. Hence, this statement is **correct**.

3. **Conclusion**:
- The incorrect statement about ribose is that it has six carbon atoms. The correct number of carbon atoms in ribose is five.

### Final Answer:
The incorrect statement about ribose is: **"It has six carbon atoms."**

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