Assertion: It has been found that for hydrogenation reaction the catalytic activity increases from group5 to group-11 metals with maximum activity being shown by groups 7-9 elements of the periodic table. Reason: For 7-9 group elements adsorption rate is maximum.

Options

A. Both assertion and reason are correct and reason is correct explanation of assertion.
B. Both assertion and reason are correct and reason is not correct explanation of assertion.
C. Assertion is true & reason is false.
D. Both are incorrect

Explanation

To solve the given question, we need to analyze the assertion and the reason provided.

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that for hydrogenation reactions, the catalytic activity of metals increases from group 5 to group 11 in the periodic table, with the maximum activity observed in groups 7 to 9.
- This means that as we move from group 5 to group 11, the metals become more effective catalysts for hydrogenation, peaking in effectiveness in groups 7 to 9.

**Hint**: Consider the properties of metals in different groups and their catalytic behavior.

2. **Understanding the Reason**:
- The reason given is that for the elements in groups 7 to 9, the rate of adsorption is maximum.
- Adsorption is crucial in catalytic reactions as it allows the reactants to come into close contact with the catalyst, facilitating the reaction.

**Hint**: Think about how adsorption relates to catalytic activity and why certain elements might have higher adsorption rates.

3. **Analyzing the Relationship**:
- Both the assertion and reason are linked. The assertion claims that the catalytic activity is highest in groups 7 to 9, and the reason explains that this is due to their maximum adsorption rate.
- The smaller atomic size and variable oxidation states of these elements contribute to their enhanced catalytic properties.

**Hint**: Reflect on how atomic size and oxidation states affect the ability of metals to act as catalysts.

4. **Conclusion**:
- Since both the assertion and reason are true, and the reason accurately explains the assertion, we conclude that both statements are correct.
- Therefore, the correct answer is that both the assertion and the reason are true, and the reason is the correct explanation of the assertion.

**Final Answer**: Both the assertion and reason are true, and the reason is the correct explanation of the assertion.