Test: Redox Reactions - JSS 2 MCQ

In the given reaction, the hydrogen is gaining oxygen and is being oxidized. This means that hydrogen is losing electrons and undergoing a process where it gains oxygen atoms. Understanding the roles of different elements in redox reactions is key to comprehending chemical transformations.

PbO is reduced to Pb and C is oxidised to CO₂.

 Zn is getting oxidised, CuO is getting reduced.

- In a redox reaction, one substance is oxidized (loses electrons) and another is reduced (gains electrons).
- Oxidation involves the gain of oxygen.
- Copper (Cu) gains oxygen to form CuO, thus it is oxidized.
- Therefore, the substance gaining oxygen and being oxidized is copper (Cu).
- Correct answer: A: Cu

In terms of hydrogen and oxygen:

Addition of hydrogen to a substance: Reduction

Removal of oxygen from a substance: Oxidation

Therefore, option A, "addition of hydrogen to a substance," correctly defines a reduction reaction.

In terms of hydrogen and oxygen:

Addition of hydrogen to a substance: Reduction

Removal of oxygen from a substance: Oxidation

Therefore, correct answer is option (b)

To identify the substances that are oxidized and reduced in the given reaction:

Reaction:

1. Oxidation involves the loss of electrons.
2. Reduction involves the gain of electrons.

• Iron (Fe) in Fe₂O₃:

  • In Fe₂O₃, iron is in the +3 oxidation state.
  • In elemental Fe, the oxidation state is 0.
  • Thus, Fe is reduced from +3 to 0.

• Aluminum (Al):

  • In elemental Al, the oxidation state is 0.
  • In Al₂O₃, aluminum is in the +3 oxidation state.
  • Thus, Al is oxidized from 0 to +3.

Substances:

• Substance reduced: Fe₂O₃ (iron is reduced to Fe).
• Substance oxidized: Al (aluminum is oxidized to Al₂O₃).

Correct Answer:

(d) Both A and B
Explanation: Fe₂O₃ is reduced, and Al is oxidized.