Question

Assertion : Iron$(III)$ catalyses the reaction between iodide and persulphate ions.
Reason : Transition metals act as catalysts.

• A. If both assertion and reason are true and reason is the correct explanation of assertion
• B. If both assertion and reason are true but reason is not the correct explanation of assertion
• C. If assertion is true but reason is false
• D. If both assertion and reason are false

Answer 1

Answer: (B)

Catalytic activity of transition metals is due to their ability to adopt multiple oxidation states and form complexes. Iron$(III)$ catalyses the reaction between iodide and persulphate ions.
$2I^- + S_2O_B^{2-} \to I_2 + 2SO^{2-}_4$
This can be explained as :
$2Fe^{3+} + 2F \to 2Fe^{2+} + I_2$
$2Fe^{2+} + S_2O_8^{2-} \to 2Fe^{3+} + 2SO_4^{2-}$