Open structure of glucose contains ___________ secondary alcoholic groups

Options

A. four
B. five
C. two
D. three

Explanation

To determine the number of secondary alcoholic groups in the open structure of glucose, we first need to understand the structure of glucose and identify the types of alcohol groups present.

### Step-by-Step Solution:

1. **Identify the Structure of Glucose**:
- Glucose is a six-carbon sugar (hexose) with the molecular formula C6H12O6. In its open-chain form, it has an aldehyde group at one end and hydroxyl (OH) groups attached to the carbon atoms.

2. **Draw the Open Structure of Glucose**:
- The open-chain structure of glucose can be represented as follows:
```
CHO - C(OH) - C(OH) - C(OH) - C(OH) - CH2OH
```
- Here, the first carbon (C1) is part of the aldehyde group (CHO), and the remaining carbons (C2 to C6) have hydroxyl groups.

3. **Identify the Types of Alcohol Groups**:
- Alcohol groups can be classified as primary, secondary, or tertiary based on the carbon atom to which the hydroxyl group is attached.
- **Primary Alcohol**: Hydroxyl group is attached to a carbon that is connected to only one other carbon.
- **Secondary Alcohol**: Hydroxyl group is attached to a carbon that is connected to two other carbons.
- **Tertiary Alcohol**: Hydroxyl group is attached to a carbon that is connected to three other carbons.

4. **Analyze Each Carbon in Glucose**:
- C1: Aldehyde group (not an alcohol)
- C2: C(OH) - This is a secondary alcohol (attached to C1 and C3).
- C3: C(OH) - This is also a secondary alcohol (attached to C2 and C4).
- C4: C(OH) - This is again a secondary alcohol (attached to C3 and C5).
- C5: C(OH) - This is a secondary alcohol (attached to C4 and C6).
- C6: CH2OH - This is a primary alcohol (attached to C5).

5. **Count the Secondary Alcohol Groups**:
- From the analysis, we find that C2, C3, C4, and C5 are secondary alcohols. Therefore, there are **4 secondary alcoholic groups** in the open structure of glucose.

### Final Answer:
The open structure of glucose contains **4 secondary alcoholic groups**.

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