AI-generated practice question — model-generated for extra practice, not a previous-year CBSE board question.
A substance that gains oxygen during a chemical reaction is oxidised. (Oxidation is defined as the gain of oxygen or loss of hydrogen.)
The definition directly from Chapter 1 states: "Oxidation is the gain of oxygen or loss of hydrogen." Examiners expect the one-word answer oxidised plus its definition for full marks. Don't confuse oxidation with reduction (which is the loss of oxygen).