The correct statements about peptides are

Options

A. A dipeptide has one peptide link between two amino acids.
B. By convention N-Terminus is kept at left and C-terminus at right in the structure of a peptide
C. If only one amino group and one carboxylic acid, group are available for reaction, then only one dipeptide can forms
D. A polypeptide with more than hundred amino acid reciduces (mol. Mass `gt 10,000`) is called a protein.

Answer

To determine the correct statements about peptides, let's analyze each option step by step.

### Step 1: Understanding Dipeptides
- **Statement A**: "A dipeptide has one peptide link between two amino acids."
- A dipeptide is formed when two amino acids are linked together by a peptide bond, which is a specific type of covalent bond. This statement is correct.

### Step 2: N-terminus and C-terminus Convention
- **Statement B**: "By convention, N-terminus is kept at left and C-terminus at right in the structure of peptide."
- In peptide structures, the N-terminus (the end with the amino group, -NH2) is indeed placed on the left, and the C-terminus (the end with the carboxylic group, -COOH) is placed on the right. This statement is also correct.

### Step 3: Availability of Functional Groups
- **Statement C**: "Only one amino group and one carboxylic group are available for the reaction, then only one dipeptide can form."
- For a dipeptide to form, you need one amino group from one amino acid and one carboxylic group from another amino acid. If only one of each is available, only one dipeptide can be formed. This statement is correct.

### Step 4: Definition of Proteins
- **Statement D**: "A polypeptide with more than 100 amino acid residues, molar mass greater than 10,000 is called a protein."
- Polypeptides that consist of more than 100 amino acids and have a molar mass greater than 10,000 Da are indeed classified as proteins. This statement is correct.

### Conclusion
All four statements about peptides are correct.

### Final Answer:
- **All statements (A, B, C, and D) about peptides are correct.**

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