…………………………….. is a tranquillizer while…………………………….. is a hallucinogen.

Explanation

**Step-by-Step Solution:**

1. **Identify the Types of Drugs**: The question requires us to identify two types of drugs: a tranquilizer and a hallucinogen.

2. **Define Tranquilizers**: Tranquilizers, also known as sedatives, are drugs that affect the central nervous system by slowing down brain activity. They are commonly used to treat anxiety, fear, tension, and disturbances of the mind.

3. **Provide an Example of a Tranquilizer**: A common example of a tranquilizer is barbiturates. These drugs are used to help individuals manage anxiety and promote relaxation.

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