Barbituric acid and its derivatives are well known as

Options

A. tranquilizers
B. antiseptics
C. analgesics
D. antipyretics.

Explanation

**Step-by-Step Solution:**

1. **Identify Barbituric Acid and Its Derivatives**:
- Barbituric acid is a chemical compound that serves as the parent structure for a class of drugs known as barbiturates. Its derivatives include substances like phenobarbital, secobarbital, amobarbital, and others.

2. **Understand the Function of Barbituric Acid Derivatives**:
- Barbiturates are primarily known for their sedative and hypnotic properties. They are commonly used to treat anxiety, insomnia, and other related conditions.

3. **Categorize the Options**:
- The question presents several categories: tranquilizers, antiseptics, analgesics, and antipyretics.
- Tranquilizers are drugs that help to calm the nervous system and are often used to treat anxiety and mental disorders.
- Antiseptics are substances that prevent the growth of disease-causing microorganisms.
- Analgesics are pain relievers.
- Antipyretics are medications that reduce fever.

4. **Match Barbituric Acid to the Correct Category**:
- Since barbituric acid and its derivatives are primarily used to treat mental disorders like anxiety and depression, they fit the definition of tranquilizers.

5. **Conclusion**:
- Therefore, the correct answer is that barbituric acid and its derivatives are well known as tranquilizers.

**Final Answer**: Barbituric acid and its derivatives are well known as tranquilizers.

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