Catalyst poisons act by

Options

A. chemically combining with the catalyst
B. getting absorbed on the active centres of the catalyst surface
C. chemical combination with anyone of the reactants
D. co-agulating the catalyst

Explanation

**Step-by-Step Solution:**

1. **Understanding Catalyst Poisons**: Catalyst poisons are substances that negatively affect the activity of a catalyst. They can interfere with the catalytic process, leading to a decrease in the efficiency of the catalyst.

2. **Mechanism of Action**: Catalyst poisons primarily act by getting adsorbed onto the surface of the catalyst. This adsorption blocks the active sites on the catalyst where the reactants would normally interact.

3. **Effect on Surface Area**: When catalyst poisons adsorb onto the catalyst's surface, they occupy space that would otherwise be available for reactants. This results in a decrease in the effective surface area of the catalyst.

4. **Impact on Reaction Rate**: With fewer active sites available for the reactants to interact with, the rate of the catalytic reaction slows down. This is because the catalyst can no longer facilitate the reaction as effectively.

5. **Use of Catalyst Poisons**: In some cases, catalyst poisons can be intentionally used to control a reaction. For example, if an intermediate product is needed and the reaction is producing unwanted products, a catalyst poison can be used to reduce the activity of the catalyst, allowing for the desired intermediate to accumulate.

6. **Conclusion**: The primary way that catalyst poisons act is by getting adsorbed on the active centers of the catalyst surface, which decreases the catalyst's effectiveness and alters the reaction pathway.

**Final Answer**: Catalyst poisons act by getting adsorbed on the active centers of the catalyst surface.

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