In pyrimidines, N is at _____position in its one 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 one ring," we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Pyrimidines**: Pyrimidines are aromatic heterocyclic organic compounds that are essential components of nucleic acids. The three main pyrimidines found in nucleic acids are cytosine, thymine, and uracil.

2. **Structure of Pyrimidines**: Pyrimidines consist of a six-membered ring structure. This ring contains four carbon atoms and two nitrogen atoms.

3. **Drawing the Structure**: To visualize the positions of the nitrogen atoms, we can draw the basic structure of a pyrimidine. The structure can be represented as follows:

```
N
/ \
C C
| |
C C
\ /
N
```

4. **Numbering the Positions**: We need to number the positions of the atoms in the pyrimidine ring. Starting from one of the nitrogen atoms, we can number the positions as follows:
- Position 1: N
- Position 2: C
- Position 3: N
- Position 4: C
- Position 5: C
- Position 6: C

5. **Identifying the Positions of Nitrogen**: From the numbering, we can see that the nitrogen atoms are located at positions 1 and 3.

6. **Conclusion**: Therefore, in pyrimidines, nitrogen is present at the 1 and 3 positions in its one ring.

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

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