Which of the following are oxidation reactions, and which are not?

To identify whether a reaction is an oxidation reaction, you need to understand the concept of oxidation.

Key Concepts of Oxidation:
A reaction is called oxidation if it involves:

• Addition of oxygen
• Removal of hydrogen
• Loss of electrons (in terms of electron transfer)

How to Identify:

1. Addition of Oxygen

• Example:
  2Mg + O₂ → 2MgO
  → Magnesium gains oxygen, so it is oxidized.

1. Removal of Hydrogen

• Example:
  H₂S → S + H₂
  → Hydrogen is removed, so oxidation occurs.

1. Electron Loss (Advanced Concept)

• Oxidation means loss of electrons in redox reactions.

Not Oxidation (Reduction):
A reaction is not oxidation if it involves:

• Removal of oxygen
• Addition of hydrogen
• Gain of electrons

Example:
CuO + H₂ → Cu + H₂O
→ Copper oxide loses oxygen, so it is reduced (not oxidized).

Important Insight:

• Oxidation and reduction always occur together. These are called redox reactions.

Exam Tip:

• Look for keywords: oxygen added = oxidation, oxygen removed = reduction.
• If options are given, analyze each reaction based on these rules.