Which of the following statements about ribose is incorrect

Options

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

Answer

To determine which statement about ribose is incorrect, we need to analyze the properties and structure of ribose.

### Step-by-Step Solution:

1. **Identify the Structure of Ribose**:
- Ribose is a pentose sugar, meaning it has **5 carbon atoms** in its structure.

2. **Understanding Functional Groups**:
- Ribose contains an **aldehyde group** (as it is an aldose sugar) at one end of the molecule. This is characterized by a carbon atom double-bonded to an oxygen atom (C=O) and single-bonded to a hydrogen atom (H).

3. **Hydroxyl Groups**:
- Ribose is classified as a **polyhydroxy compound**, which means it has multiple hydroxyl (–OH) groups attached to its carbon atoms. In ribose, there are four hydroxyl groups.

4. **Optical Activity**:
- Ribose exhibits **optical activity** due to the presence of multiple chiral centers (as it has more than one carbon atom bonded to four different substituents).

5. **Evaluating the Statements**:
- Now, we need to evaluate the statements given in the question:
- Statement about the number of carbon atoms: **Correct** (Ribose has 5 carbon atoms).
- Statement about it being a polyhydroxy compound: **Correct** (Ribose has multiple hydroxyl groups).
- Statement about it containing an aldehyde group: **Correct** (Ribose is an aldose).
- Statement about the number of carbon atoms being 6: **Incorrect** (Ribose has only 5 carbon atoms).

6. **Conclusion**:
- The incorrect statement about ribose is that it has **6 carbon atoms**. Ribose actually has **5 carbon atoms**.

### Final Answer:
The incorrect statement about ribose is that it has **6 carbon atoms**.