The substance used as a fast drying agent in the laboratory is:

Options

A. `Na_(3)PO_(4)`
B. `P_(4)O_(10)`
C. charcoal
D. anhydrous calcium chloride

Explanation

To determine the substance used as a fast drying agent in the laboratory, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Purpose of Drying Agents**:
- Drying agents are substances that absorb moisture from other substances, making them useful in laboratory settings for drying solvents and other liquids.

2. **List Common Drying Agents**:
- Some commonly used drying agents in laboratories include:
- Anhydrous calcium chloride (CaCl₂)
- Sodium sulfate (Na₂SO₄)
- Calcium sulfate (CaSO₄)
- Magnesium sulfate (MgSO₄)

3. **Focus on Anhydrous Forms**:
- It is important to note that these drying agents must be in their anhydrous (water-free) forms to effectively absorb moisture.

4. **Evaluate the Options**:
- From the options provided, we need to identify which substance is recognized as a fast drying agent.
- Anhydrous calcium chloride is widely known for its efficiency in drying due to its high hygroscopic nature.

5. **Select the Correct Answer**:
- Based on the evaluation, the correct answer is **Anhydrous Calcium Chloride**.

### Final Answer:
The substance used as a fast drying agent in the laboratory is **Anhydrous Calcium Chloride**.

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