Which of the following chemicals is used for poisoning the specimens in herbarium technique?

Options

A. CO
B. `AgNO_3`
C. HCL
D. `HgCl_2`

Answer

To answer the question regarding which chemical is used for poisoning specimens in the herbarium technique, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Herbarium Technique**:
- A herbarium is a collection of dried plant specimens that are mounted on sheets of paper. The purpose of creating a herbarium is to preserve plant specimens for study and reference.

2. **Identify the Purpose of Poisoning**:
- The process of poisoning is used to prevent decay and to preserve the plant specimens in their dried state. This is essential for long-term storage and study.

3. **Evaluate the Given Options**:
- The options provided are:
- A) Carbon monoxide (Cu)
- B) Silver nitrate (AgNO3)
- C) Hydrochloric acid (HCl)
- D) Mercuric chloride (HgCl2)

4. **Know the Correct Chemical**:
- Among the options, mercuric chloride (HgCl2) is commonly used in the herbarium technique. It is used in an alcoholic solution to poison the plant specimens effectively.

5. **Conclude the Answer**:
- Therefore, the correct answer to the question is **D) HgCl2 (mercuric chloride)**.