Mineral acids are usually added to commercial hydrogen peroxide to

Analyze the question: Why do manufacturers add mineral acids (such as dilute H₂SO₄ or H₃PO₄) to commercial hydrogen peroxide?

Concept: Hydrogen peroxide is unstable and tends to decompose into water and oxygen:

2H₂O₂ → 2H₂O + O₂

This decomposition is catalysed by several things:

• Light
• Heat
• Traces of alkali
• Metal ions and impurities (e.g. Fe³⁺, Mn²⁺) and rough surfaces

H₂O₂ is more stable in slightly acidic conditions. Alkaline conditions speed up its breakdown. So manufacturers:

• Store it in dark or opaque bottles (to keep out light)
• Add a small amount of mineral acid, and sometimes stabilisers such as phosphoric acid, to keep the solution slightly acidic and slow the decomposition.

Solution, going through the options:

• A. Oxidize it: Wrong. Acid is not added to oxidize H₂O₂, and doing so would not be useful.
• B. Decompose it: Wrong. This is the opposite of the purpose, since manufacturers want it to last.
• C. Minimize its decomposition: Correct. The acid makes the solution slightly acidic and counters traces of alkali, which stabilises the peroxide and slows its breakdown.
• D. Reduce it to water and oxygen: Wrong. This is just the decomposition reaction, which the acid is meant to prevent.

Answer: C. Minimize its decomposition

Exam tip: Remember "H₂O₂ is happy in acid, unhappy in alkali, light and heat." Whenever you see a question on storing or stabilising H₂O₂, think: dark bottle, cool place, a little acid. Any option about speeding up decomposition is a distractor.