Which of the following statements are correct ?

Options

A. `alpha`- and `beta`-D-glucopyranose are anomers
B. `beta`-D - glucopyranose is more stable than `alpha-D`- glucopyranose
C. galactose is a `C_(4)` - epimer of glucose
D. invert sugar is laevorotatory

Answer

To determine which statements are correct regarding the biomolecules mentioned, let's analyze each statement step by step.

### Step 1: Analyze Statement A
**Statement A**: Alpha and beta D-glucopyranose are anomers.

- **Explanation**: Anomers are a specific type of stereoisomer that differ at the anomeric carbon, which is the carbon that is derived from the carbonyl carbon (C=O) during the formation of a cyclic structure. In D-glucose, the anomeric carbon is C1. Alpha D-glucopyranose has the hydroxyl group (OH) on the anomeric carbon (C1) pointing down, while in beta D-glucopyranose, the OH is pointing up. Therefore, they are indeed anomers.

**Conclusion**: Statement A is correct.

### Step 2: Analyze Statement B
**Statement B**: Beta D-glucopyranose is more stable than alpha D-glucopyranose.

- **Explanation**: In the cyclic forms of glucose, the stability is influenced by the position of substituents around the anomeric carbon. In beta D-glucopyranose, the OH group on the anomeric carbon is in an equatorial position, which minimizes steric hindrance and increases stability. In contrast, in alpha D-glucopyranose, the OH group is in an axial position, which is less stable due to steric interactions with other axial hydrogens. Thus, beta D-glucopyranose is indeed more stable than alpha D-glucopyranose.

**Conclusion**: Statement B is correct.

### Step 3: Analyze Statement C
**Statement C**: Galactose is a C4 epimer of glucose.

- **Explanation**: Epimers are a type of diastereomer that differ at only one specific carbon atom. In the case of galactose and glucose, they differ at the C4 position. In glucose, the hydroxyl group on C4 is on the right, while in galactose, it is on the left. This confirms that galactose is indeed a C4 epimer of glucose.

**Conclusion**: Statement C is correct.

### Step 4: Analyze Statement D
**Statement D**: Invert sugar is a levorotatory.

- **Explanation**: Invert sugar is a mixture of glucose and fructose obtained by hydrolyzing sucrose. It is called "invert" because it rotates plane-polarized light in the opposite direction compared to sucrose. Invert sugar can be either levorotatory (rotating light to the left) or dextrorotatory (rotating light to the right), depending on the specific composition of the sugars in the mixture. However, it is commonly referred to as levorotatory due to the predominance of fructose, which is typically levorotatory.

**Conclusion**: Statement D is correct.

### Final Conclusion
All the statements A, B, C, and D are correct.

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