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NEET CHEMISTRYElectrochemistryMedium

Question

Zinc can be coated on iron to produce galvanised iron but the reverse is not possible. It is because

A

zinc is lighter than iron

B

zinc has lower melting point than iron

C

zinc has lower negative electrode potential than iron

D

zinc has higher negative electrode potential than iron

Step-by-Step Solution

The standard reduction potential of zinc (EZn2+/Zn=0.76 VE^\circ_{\text{Zn}^{2+}/\text{Zn}} = -0.76 \text{ V}) is more negative than that of iron (EFe2+/Fe=0.44 VE^\circ_{\text{Fe}^{2+}/\text{Fe}} = -0.44 \text{ V}). This means zinc has a higher negative electrode potential than iron, making it a stronger reducing agent. When zinc is coated on iron (galvanisation), zinc acts as a sacrificial anode and undergoes oxidation preferentially, protecting the iron from corrosion. The reverse is not possible because iron, being a weaker reducing agent with a lower negative electrode potential, cannot protect zinc.

Exam Context & Concepts Covered

This question aligns with the NEET CHEMISTRY syllabus, specifically targeting concepts from Electrochemistry. Mastering this topic is crucial for scoring well in the upcoming medical entrance examinations. Solving conceptually related problems will help you understand the nuances of these concepts and improve your problem-solving speed.

CHEMISTRYElectrochemistrycoatedproducegalvanisedreversepossible

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