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 = gain of electrons, loss of oxygen, gain of hydrogen, or \(\downarrow\) oxidation number.
Step 2: Evaluate options.
(1) Gain of oxygen \(\Rightarrow\) oxidation (not reduction).
(2) Increase in oxidation state \(\Rightarrow\) oxidation.
(3) Gain of hydrogen \(\Rightarrow\) reduction (correct).
(4) Loss of electrons \(\Rightarrow\) oxidation (reduction is gain of electrons).
Final Answer: \[ \boxed{\text{gains hydrogen}} \]