According to the adsoption theory of catalysis ,the speed of the reaction increases because:

Options

A. in the process of adsorption , the activation energy of the molecules becomes large
B. adsorption produces heat which increases the speed of the reaction
C. adsorption lowers the activation energy of the reaction
D. adsorption increases the activation energy of the reaction

Answer

To solve the question regarding the adsorption theory of catalysis, we will analyze the options provided and determine which one correctly explains why the speed of the reaction increases.

### Step-by-Step Solution:

1. **Understanding Catalysis**:
- Catalysts are substances that increase the rate of a chemical reaction without being consumed in the process. They work by providing an alternative pathway for the reaction with a lower activation energy.

2. **Defining Adsorption**:
- Adsorption is the process by which atoms, ions, or molecules from a gas, liquid, or dissolved solid adhere to a surface. In catalysis, the reactants are adsorbed onto the surface of the catalyst.

3. **Analyzing the Options**:
- **Option 1**: "In the process of adsorption, the activation energy of the molecules become large."
- This statement is incorrect because an increase in activation energy would slow down the reaction, not speed it up.

- **Option 2**: "Adsorption produces heat, which increases the speed of the reaction."
- While some reactions may be exothermic, this is not a general principle of catalysis and does not directly explain the increase in reaction rate.

- **Option 3**: "Adsorption lowers the activation energy of the reaction."
- This statement is correct. The presence of a catalyst lowers the activation energy required for the reaction to occur, thus increasing the reaction rate.

- **Option 4**: "Adsorption increases the activation energy of the reaction."
- This is also incorrect as increasing the activation energy would hinder the reaction rate.

4. **Conclusion**:
- Based on the analysis, the correct answer is **Option 3**: "Adsorption lowers the activation energy of the reaction."

### Final Answer:
**Option 3** is the correct answer: "Adsorption lowers the activation energy of the reaction."

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