The correct statements about anomers are

Options

A. Anomers have different stereochemistry at `C-1` (anomeric carbon)
B. `alpha-D`glucopyranose and `beta-D-`glucopyranose can be crystallised and purified
C. When pure `alpha-D-`glucopyranose is dissolved in water is optical rotation slowly changes
D. When pure `alpha`-D-glucopyranose and one carboxylic acid, group are available for reaction, then only one dipeptide can forms.

Explanation

To determine the correct statements about anomers, we will analyze each statement one by one.

### Step-by-Step Solution:

1. **Understanding Anomers**:
Anomers are a type of stereoisomer that differ at the anomeric carbon (C1) in a cyclic sugar. This is crucial to understanding the first statement.

2. **Evaluating Statement A**:
- **Statement**: Anomers have different stereochemistry at C1, which is called the anomeric carbon.
- **Analysis**: This statement is **correct** because anomers are defined by their difference in configuration at the anomeric carbon.

3. **Evaluating Statement B**:
- **Statement**: Alpha-D-glucopyranose and beta-D-glucopyranose can be crystallized and purified.
- **Analysis**: This statement is also **correct**. The two forms have different melting points (146°C for alpha-D-glucose and 150°C for beta-D-glucose), allowing for their separation through crystallization.

4. **Evaluating Statement C**:
- **Statement**: When pure alpha-D-glucopyranose is dissolved in water, its optical rotation slowly changes.
- **Analysis**: This statement is **correct** due to the phenomenon of mutarotation. When alpha-D-glucose is dissolved in water, it can interconvert with beta-D-glucose and the open-chain form, leading to a change in optical rotation over time.

5. **Evaluating Statement D**:
- **Statement**: When pure alpha-D-glucopyranose and one carboxylic acid group are available for the reaction, then only one dipeptide can form.
- **Analysis**: This statement is **false**. Dipeptides are formed between an amino group and a carboxylic acid group. Since alpha-D-glucopyranose does not contain an amino group, it cannot form a dipeptide.

### Conclusion:
The correct statements about anomers are A, B, and C.

### Final Answer:
The correct statements about anomers are:
- A: Anomers have different stereochemistry at C1.
- B: Alpha-D-glucopyranose and beta-D-glucopyranose can be crystallized and purified.
- C: When pure alpha-D-glucopyranose is dissolved in water, its optical rotation slowly changes.