Answer: 3% (household), 30% (laboratory), 90%+ (industrial/rocket fuel).
- A 3% (household), 30% (laboratory), 90%+ (industrial/rocket fuel)
- B Usually supplied as pure 100% anhydrous liquid according to standard textbooks
- C Fixed at 1% concentration for all commercial uses in general practice
- D A single standard grade of 50% for every application as frequently described
Correct answer: A. 3% (household), 30% (laboratory), 90%+ (industrial/rocket fuel)
Explanation: H<sub>2</sub>O<sub>2</sub> is sold in different concentrations: 3% (antiseptic), ~6-9% (hair bleaching), ~30% (lab), >90% (propellant).
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.