Reactions involve the gain or loss of oxygen or hydrogen by substances.
Statement A: Oxidation is the loss of oxygen and gain of hydrogen.
Statement B: Reduction is the loss of hydrogen and gain of oxygen.
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → Both statements A and B are incorrect.
In terms of oxygen and hydrogen, oxidation is the gain of oxygen or the loss of hydrogen, and reduction is the loss of oxygen or the gain of hydrogen. In \(\ce{CuO + H2 -> Cu + H2O}\), copper oxide loses oxygen and is reduced, while hydrogen gains oxygen and is oxidised.
Statement A: Oxidation is the loss of oxygen and gain of hydrogen. Incorrect. Losing oxygen and gaining hydrogen is reduction; oxidation is the opposite, as when hydrogen becomes water above.
Statement B: Reduction is the loss of hydrogen and gain of oxygen. Incorrect. Losing hydrogen and gaining oxygen is oxidation; reduction is the opposite, as when copper oxide becomes copper above.