The adsorption of a gas by palladium is commonly known as ………………….

Explanation

To solve the question regarding the adsorption of a gas by palladium, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Adsorption**:
- Adsorption is the process where atoms, ions, or molecules from a gas, liquid, or dissolved solid adhere to a surface. In this case, we are focusing on a gas being adsorbed by a solid, which is palladium.

2. **Identifying the Gas**:
- The question does not specify which gas is being adsorbed, but a common example of gas adsorption by palladium is hydrogen.

3. **Defining the Process**:
- The specific term used for the adsorption of hydrogen gas by palladium is known as "occlusion." This term refers to the process where the gas is not just adsorbed on the surface but is also absorbed into the bulk of the material.

4. **Properties of Occluded Gas**:
- The occluded gas (in this case, hydrogen) behaves differently than ordinary gas. The adsorbed hydrogen is often more reactive than hydrogen in its normal gaseous state.

5. **Conclusion**:
- Therefore, the answer to the question is that the adsorption of a gas by palladium is commonly known as "occlusion."

### Final Answer:
The adsorption of a gas by palladium is commonly known as **occlusion**.