Which of the following is an example of absorption?

Options

A. Water on silica gel
B. Water on calcium chloride
C. Hydrogen on finely divided nickel
D. Oxygen on metal surface

Explanation

To determine which of the following is an example of absorption, we need to understand the concept of absorption in surface chemistry.

### Step-by-Step Solution:

1. **Define Absorption**: Absorption is a process where a substance (the absorbate) is taken up by another substance (the absorbent) and penetrates into its bulk. This means that the concentration of the absorbate increases in the bulk of the absorbent.

2. **Identify the Options**: Although the options are not provided in the question, we will focus on the example given in the transcript: water being added to calcium chloride.

3. **Analyze the Example**: When water (H2O) is added to the surface of calcium chloride (CaCl2), the water molecules do not just stay on the surface; they penetrate into the calcium chloride. This means that the concentration of water molecules increases in the bulk of calcium chloride.

4. **Conclusion**: Since the example of water on calcium chloride illustrates the process of absorption (where the water molecules are absorbed into the bulk of the calcium chloride), we can conclude that this is indeed an example of absorption.

5. **Correct Option**: Therefore, the correct answer to the question is that water on calcium chloride is an example of absorption.