For the following Assertion and Reason, the correct option is: Assertion: For hydrogenation reactions, the catalytic…
d & f-Block Elements · Class 12 · JEE Main Previous Year Question
For the following Assertion and Reason, the correct option is:
Assertion: For hydrogenation reactions, the catalytic activity increases from Group 5 to Group 11 metals with maximum activity shown by Group 7–9 elements.
Reason: The reactants are most strongly adsorbed on Group 7–9 elements.
- a✓
The assertion is true, but the reason is false
- b
Both assertion and reason are false
- c
Both assertion and reason are true and the reason is the correct explanation for the assertion
- d
Both assertion and reason are true but the reason is not the correct explanation for the assertion
The assertion is true, but the reason is false
Assertion: Catalytic activity for hydrogenation increases from Group 5 → Group 11, with maximum at Group 7–9 (Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt). TRUE ✓
Reason: The reason given is that reactants are most strongly adsorbed on Group 7–9 elements. This is FALSE ✗
Correct explanation: The optimum catalytic activity at Group 7–9 is because:
- If adsorption is too weak (Group 11): reactants don't bind well
- If adsorption is too strong (Group 5–6): products cannot desorb
- Group 7–9 shows intermediate adsorption — neither too strong nor too weak — which is optimal for catalysis (Sabatier's principle)
So the assertion is correct, but the reason is incorrect (it should say intermediate adsorption, not strongest adsorption).
Answer: Option (1)
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