Which of the following substance (s) is/are used in laboratory for drying purposes ?

Options

A. Anhydrous `P_(2)O_(5)`
B. Graphite
C. Anhydrous `CaCI_(2)`
D. `Na_(3)PO_(4)`

Answer

To determine which substances are used in laboratories for drying purposes, we need to identify hygroscopic and deliquescent substances from the given options. Here’s a step-by-step solution:

### Step 1: Understand the Terms
- **Hygroscopic Substances**: These are substances that absorb moisture from the air. They can be used as drying agents.
- **Deliquescent Substances**: These substances absorb moisture from the air to the extent that they dissolve in the absorbed water, forming a solution.

### Step 2: Analyze the Given Options
We need to evaluate each of the four substances provided in the question to see if they are hygroscopic or deliquescent.

1. **Anhydrous P2O5 (Phosphorus Pentoxide)**:
- This is a known drying agent. It is highly hygroscopic and can absorb water from the atmosphere to form phosphoric acid (H3PO4).
- **Conclusion**: Used for drying.

2. **Anhydrous CaCl2 (Calcium Chloride)**:
- This substance is also hygroscopic and is commonly used as a drying agent. It absorbs moisture and can form a hydrated compound (CaCl2·2H2O).
- **Conclusion**: Used for drying.

3. **Graphite**:
- Graphite does not absorb moisture and is not used as a drying agent.
- **Conclusion**: Not used for drying.

4. **Na3PO4 (Sodium Phosphate)**:
- Sodium phosphate is not hygroscopic and does not serve as a drying agent.
- **Conclusion**: Not used for drying.

### Step 3: Final Conclusion
Based on the analysis:
- **Anhydrous P2O5** and **Anhydrous CaCl2** are the substances used in laboratories for drying purposes.
- **Graphite** and **Na3PO4** are not used for drying.

### Summary of the Answer:
The substances used in laboratories for drying purposes are:
- Anhydrous P2O5
- Anhydrous CaCl2