Which of the following is not suitable for use in a desiccator to dry substances

Options

A. Conc. `H_(2)SO_(4)`
B. `Na_(2)SO_(4)`
C. `CaCl_(2)`
D. `P_(4)O_(10)`

Answer

To determine which substance is not suitable for use in a desiccator to dry substances, we need to understand the properties of desiccants and the nature of the substances listed.

### Step-by-Step Solution:

1. **Understand the Purpose of a Desiccator**:
- A desiccator is a sealed container used to keep moisture-sensitive items dry. It typically contains a drying agent (desiccant) that absorbs moisture from the air inside the container.

2. **Identify the Characteristics of Desiccants**:
- Desiccants are substances that are hygroscopic in nature. This means they have the ability to absorb moisture from the air.

3. **Evaluate the Given Options**:
- We need to analyze the substances provided in the options to identify which one does not possess hygroscopic properties.

4. **Analyze Concentrated H2SO4**:
- Concentrated sulfuric acid (H2SO4) is known for its strong dehydrating properties. However, it is not hygroscopic in the sense that it does not merely absorb moisture from the air; instead, it reacts with water and can cause significant chemical changes.

5. **Conclusion**:
- Therefore, the substance that is not suitable for use in a desiccator to dry substances is **concentrated H2SO4**.

### Final Answer:
- The substance that is not suitable for use in a desiccator to dry substances is **concentrated H2SO4**.