In pyrimidines, N is at _____position in its new ring.

Options

A. 1,3
B. 7,9
C. 1
D. 1&9

Answer

To answer the question "In pyrimidines, N is at _____ position in its new ring," we will analyze the structure of pyrimidines step by step.

### Step-by-Step Solution:

1. **Understanding Pyrimidines**:
- Pyrimidines are one of the two types of nitrogenous bases found in nucleotides, the other being purines. The three main pyrimidines are cytosine, thymine, and uracil.

2. **Structure of Pyrimidines**:
- Pyrimidines have a six-membered ring structure that includes nitrogen atoms. The general formula for pyrimidines is C4H4N2.

3. **Identifying Positions of Nitrogen**:
- In the pyrimidine ring, the positions are numbered starting from one of the nitrogen atoms.
- The nitrogen atoms are typically located at specific positions within the ring.

4. **Analyzing Specific Pyrimidines**:
- **Cytosine**: In the structure of cytosine, nitrogen is present at the 1st and 3rd positions.
- **Uracil**: In uracil, nitrogen is also found at the 1st and 3rd positions.
- **Thymine**: Similarly, in thymine, nitrogen is located at the 1st and 3rd positions.

5. **Conclusion**:
- From the analysis of the structures of cytosine, uracil, and thymine, we can conclude that in pyrimidines, nitrogen (N) is consistently located at the 1st and 3rd positions in the ring.

### Final Answer:
In pyrimidines, N is at **1, 3** position in its new ring.

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