Question

Reduction has taken place if a substance......

• A. gains oxygen
• B. increase its oxidation state
• C. gains hydrogen
• D. loses electrons

Hint:

OIL RIG: Oxidation Is Loss (of \(e^-\)), Reduction Is Gain (of \(e^-\)). Reduction often = hydrogenation.

Answer 1

The Correct Option is C

Step 1: Recall equivalent definitions.
Reduction is defined as the gain of electrons, loss of oxygen, gain of hydrogen, or a \(\downarrow\) in oxidation number.
Step 2: Evaluate options.
(1) Gain of oxygen implies oxidation, not reduction.
(2) Increase in oxidation state implies oxidation.
(3) Gain of hydrogen implies reduction (correct).
(4) Loss of electrons implies oxidation (reduction is the gain of electrons).
Final Answer: \[ \boxed{\text{gains hydrogen}} \]