Which one of the following is not an example of a redox reaction?
AlCl₃ + 3H₂O → Al(OH)₃ + 3HCl
2NaH → 2Na + H₂
4Fe + 3O₂ → 2Fe₂O₃
CuSO₄ + Zn → Cu + ZnSO₄
Answer is Right!
Answer is Wrong!
This question was previously asked in
UPSC NDA-1 – 2022
– Oxidation is an increase in oxidation state (loss of electrons).
– Reduction is a decrease in oxidation state (gain of electrons).
– Let’s analyze the oxidation states in each reaction:
– A) AlCl₃ (+3, -1) + H₂O (+1, -2) → Al(OH)₃ (+3, -2, +1) + HCl (+1, -1). Oxidation states of all elements remain unchanged.
– B) 2NaH (+1, -1) → 2Na (0) + H₂ (0). Na changes from +1 to 0 (reduction), H changes from -1 to 0 (oxidation). Redox.
– C) 4Fe (0) + 3O₂ (0) → 2Fe₂O₃ (+3, -2). Fe changes from 0 to +3 (oxidation), O changes from 0 to -2 (reduction). Redox.
– D) CuSO₄ (+2, -2) + Zn (0) → Cu (0) + ZnSO₄ (+2, -2). Cu changes from +2 to 0 (reduction), Zn changes from 0 to +2 (oxidation). Redox.