Answer: H 2 O 2 + 2Fe 2+ + 2H+ → 2Fe 3+ + 2H 2 O.
- A H<sub>2</sub>O<sub>2</sub> + 2Fe<sup>2+</sup> + 2H+ → 2Fe<sup>3+</sup> + 2H<sub>2</sub>O
- B 2H<sub>2</sub>O<sub>2</sub> → 2H<sub>2</sub>O + O<sub>2</sub> (decomposition)
- C H<sub>2</sub>O<sub>2</sub> + 2KMnO<sub>4</sub> → products
- D H<sub>2</sub>O<sub>2</sub> + Na<sub>2</sub>SO<sub>3</sub> → Na<sub>2</sub>SO<sub>4</sub> + H<sub>2</sub>O
Correct answer: A. H<sub>2</sub>O<sub>2</sub> + 2Fe<sup>2+</sup> + 2H+ → 2Fe<sup>3+</sup> + 2H<sub>2</sub>O
Explanation: H<sub>2</sub>O<sub>2</sub> oxidises Fe<sup>2+</sup> to Fe<sup>3+</sup> in the Fenton reaction; this demonstrates its oxidising role in acidic solution.
Each water molecule's O-H bonds (covalent, solid) can hydrogen-bond (dashed) to neighbouring molecules, forming an extended network responsible for water's unusually high boiling point and density anomaly.
Concept context
The simplest and most abundant element in the universe. Study its unique position in the periodic table, isotopes (protium, deuterium, tritium), properties of water and hydrogen peroxide, and industrial uses.