A catalyst promoter……….. The efficiency of a catalyst while a poison…………….. The efficiency of the catalyst.

Answer

To solve the question, we need to fill in the blanks with the appropriate terms that describe the effects of a catalyst promoter and a catalyst poison on the efficiency of a catalyst.

### Step-by-Step Solution:

1. **Understanding the Terms**:
- A **catalyst promoter** is a substance that enhances the activity of a catalyst.
- A **catalyst poison** is a substance that reduces the activity of a catalyst.

2. **Filling in the First Blank**:
- The sentence states: "A catalyst promoter ______ the efficiency of a catalyst."
- Since a catalyst promoter increases the efficiency, we fill in the blank with the word **"increases"**.

3. **Filling in the Second Blank**:
- The sentence states: "While a poison ______ the efficiency of the catalyst."
- Since a catalyst poison decreases the efficiency, we fill in the blank with the word **"decreases"**.

4. **Final Sentence**:
- The completed sentence reads: "A catalyst promoter **increases** the efficiency of a catalyst while a poison **decreases** the efficiency of the catalyst."

### Final Answer:
A catalyst promoter **increases** the efficiency of a catalyst while a poison **decreases** the efficiency of the catalyst.