Reduction is the process of

Step 1: Analyze the question We are asked to identify which option correctly defines reduction, the opposite of oxidation.

Step 2: The concept Reduction can be defined in several ways:

• Gain of electrons (electronic definition)
• Gain of hydrogen
• Loss of oxygen
• Decrease in oxidation number
• Removal of electronegative elements

Oxidation is the opposite:

• Loss of electrons
• Loss of hydrogen
• Gain of oxygen
• Increase in oxidation number
• Addition of electronegative elements

Step 3: Check each option

• A. Loss of electron: This is oxidation, not reduction. ✗
• B. Loss of hydrogen: This is oxidation. ✗
• C. Loss of oxygen: This is reduction. Example: CuO + H₂ → Cu + H₂O. Copper(II) oxide loses oxygen, so it is reduced. ✓
• D. Addition of electronegative elements: This is oxidation, since oxygen and chlorine are electronegative. ✗

Step 4: Answer Reduction is the process of loss of oxygen, which is option C.

Tip: Remember OIL RIG: Oxidation Is Loss (of electrons), Reduction Is Gain (of electrons). For oxygen and hydrogen, flip it: reduction is loss of oxygen and gain of hydrogen. If an option lists a "loss" and it is not electrons, check whether it is oxygen, because that signals reduction.