Which of the following is not tranquilizer?

Options

A. Luminal
B. Seconal
C. Reserpine
D. Piperazine

Explanation

To determine which of the following options is not a tranquilizer, we need to understand what tranquilizers are and identify the options provided.

### Step-by-Step Solution:

1. **Understanding Tranquilizers**:
- Tranquilizers are substances that induce calmness and reduce stress. They are often used to treat anxiety and other related conditions.

2. **Identifying the Chemical Structure**:
- Many tranquilizers are derivatives of barbituric acid. While barbituric acid itself is not a tranquilizer, its derivatives are.

3. **Analyzing the Options**:
- **Option A: Luminol** - This is a derivative of barbituric acid and is classified as a barbiturate, which is a tranquilizer.
- **Option B: Seconal** - This is also a derivative of barbituric acid and is classified as a barbiturate, making it a tranquilizer as well.
- **Option C: Reserpine** - This is an alkaloid that acts like a tranquilizer but is not a derivative of barbituric acid. It is used for its calming effects.
- **Option D: Piperazine** - This is an antibiotic and does not have tranquilizing properties.

4. **Conclusion**:
- Among the options provided, **Piperazine** is the only one that is not a tranquilizer. Therefore, the correct answer is **Option D: Piperazine**.

### Final Answer:
**The option that is not a tranquilizer is Option D: Piperazine.**