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NEET CHEMISTRYThe d-and f-Block ElementsMedium

Question

Which of the following processes does not involve the oxidation of iron?

A

Rusting of iron sheets

B

Decolourisation of blue CuSO4\text{CuSO}_4 solution by iron

C

Formation of Fe(CO)5\text{Fe}(\text{CO})_5 from Fe\text{Fe}

D

Liberation of H2\text{H}_2 from steam by iron at high temperature

Step-by-Step Solution

Let us analyze the change in the oxidation state of iron in each process:

  1. Rusting of iron sheets: Iron reacts with oxygen and moisture to form rust, which is hydrated iron(III) oxide (Fe2O3⋅xH2O\text{Fe}_2\text{O}_3 \cdot x\text{H}_2\text{O}). Here, the oxidation state of Fe\text{Fe} changes from 00 to +3+3. This is an oxidation process.
  2. Decolourisation of blue CuSO4\text{CuSO}_4 solution by iron: Iron displaces copper from copper sulphate solution: Fe+CuSO4→FeSO4+Cu\text{Fe} + \text{CuSO}_4 \rightarrow \text{FeSO}_4 + \text{Cu}. Here, the oxidation state of Fe\text{Fe} changes from 00 to +2+2. This is an oxidation process.
  3. Formation of Fe(CO)5\text{Fe}(\text{CO})_5 from Fe\text{Fe}: In the metal carbonyl complex pentacarbonyliron(0), Fe(CO)5\text{Fe}(\text{CO})_5, the ligand carbon monoxide (CO\text{CO}) is a neutral molecule. Therefore, the oxidation state of iron remains 00. This process does not involve the oxidation of iron.
  4. Liberation of H2\text{H}_2 from steam by iron at high temperature: Iron reacts with steam to form iron(II,III) oxide (Fe3O4\text{Fe}_3\text{O}_4) and hydrogen gas: 3Fe+4H2O→Fe3O4+4H23\text{Fe} + 4\text{H}_2\text{O} \rightarrow \text{Fe}_3\text{O}_4 + 4\text{H}_2. Here, the oxidation state of Fe\text{Fe} changes from 00 to an average of +8/3+8/3 (a mixture of +2+2 and +3+3). This is an oxidation process.

Exam Context & Concepts Covered

This question aligns with the NEET CHEMISTRY syllabus, specifically targeting concepts from The d-and f-Block Elements. 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.

CHEMISTRYThe d-and f-Block Elementsfollowingprocessesinvolveoxidation

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