Identifying the Incorrect Statement about Hydrogen Peroxide (H₂O₂)

Let's analyze each statement step by step:

Step 1: Evaluate "It can act only as an oxidizing agent"

Hydrogen peroxide can act as both an oxidizing agent and a reducing agent. For example:

As oxidizing agent: $H_2{O}_2+2I^{-}+2H^{+}\to I_2+2H_{2}O$

As reducing agent: $H_2{O}_2+{\mathrm{Cl}}_2\to 2\mathrm{HCl}+O_2$

This statement is incorrect because H₂O₂ can act as both.

Step 2: Evaluate "It decomposes on exposure to light"

Hydrogen peroxide is photosensitive and decomposes when exposed to light according to:

$2H_2{O}_2\to 2H_{2}O+O_2$

This statement is correct.

Step 3: Evaluate storage conditions

H₂O₂ is stored in plastic or wax-lined glass bottles to prevent catalytic decomposition by rough glass surfaces, and in dark to prevent photodecomposition. Both storage-related statements are correct.

Final Answer

The incorrect statement is: "It can act only as an oxidizing agent"

Related Concepts

Redox Chemistry of H₂O₂

Hydrogen peroxide exhibits dual behavior because oxygen in H₂O₂ has an oxidation state of -1, which can both decrease to -2 (reduction) or increase to 0 (oxidation).

Important Formulae

Decomposition: $2H_2{O}_2\to 2H_{2}O+O_2$

Oxidation half-reaction: $H_2{O}_2\to O_2+2H^{+}+2e^{-}$

Reduction half-reaction: $H_2{O}_2+2H^{+}+2e^{-}\to 2H_{2}O$

Storage Theory

H₂O₂ requires special storage because:

• Light catalyzes decomposition
• Dust particles and rough surfaces provide nucleation sites for decomposition
• Alkaline conditions accelerate decomposition
• Traces of metal ions (Fe²⁺, Mn²⁺) catalyze decomposition