DNA has equal number of adenine and thymine residuces (A=T) and equal number of guanine and cytosine (G=C). These relationships are known as

Options

A. Chargaff's rule
B. Coulomb's law
C. Le Chatelier's priciple
D. Van't Hoff plot

Answer

To solve the question regarding the relationships in DNA, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Components of DNA**:
- DNA is made up of four nitrogenous bases: adenine (A), thymine (T), guanine (G), and cytosine (C).
- The question states that there are equal numbers of adenine and thymine (A = T) and equal numbers of guanine and cytosine (G = C).

2. **Identifying the Relationship**:
- The relationships A = T and G = C indicate a specific pairing and stoichiometric balance in the DNA structure.
- This pairing is crucial for the double helical structure of DNA, where A pairs with T and G pairs with C.

3. **Recalling the Relevant Rule**:
- The rule that describes this relationship is known as Chargaff's rule.
- Chargaff's rule states that in any given DNA molecule, the amount of adenine is equal to the amount of thymine, and the amount of guanine is equal to the amount of cytosine.

4. **Eliminating Other Options**:
- Coulomb's law pertains to electric forces and is not related to DNA.
- Le Chatelier's principle deals with chemical equilibria and does not apply here.
- Van 't Hoff plot is used for thermodynamic calculations and is also irrelevant to the question.

5. **Conclusion**:
- Therefore, the correct answer to the question is Chargaff's rule.

### Final Answer:
The relationships are known as **Chargaff's rule**.

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