The green colour of Fe²+ changes to brown Fe³+ by

 The green colour of Fe²+ changes to brown Fe³+ by

A. substitution

B. oxidation

C. reduction

D. conversion

The correct answer is B. Oxidation ✅

Explanation:

• Fe²⁺ (iron II ion) is green in solution.

• When it loses an electron, it becomes Fe³⁺ (iron III ion), which is brown/yellowish-brown.

Fe²+-> Fe³+ + e^-

Loss of electrons = Oxidation

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Why others are wrong:

• Substitution → exchange of atoms/groups

• Reduction → gain of electrons

• Conversion → not a redox term

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👉 Final Answer: B. Oxidation

PQN: 3