Question

Which of the following is an example of a redox reaction?

• A. NaCl dissolving in water
• B. \( \mathrm{2H_2O_2\ (aq) \rightarrow 2H_2O\ (l) + O_2\ (g)} \)
• C. NaOH dissolving in water
• D. \( \mathrm{CaCO_3\ (s) \rightarrow CaO\ (s) + CO_2\ (g)} \)

Hint:

In redox reactions, always look for changes in oxidation numbers to identify which species are oxidized and reduced.

Answer 1

The Correct Option is B

A redox reaction is a chemical reaction involving both reduction and oxidation. In the decomposition of hydrogen peroxide (\( \mathrm{H_2O_2} \)), oxygen is reduced (from \( \mathrm{-1} \) in \( \mathrm{H_2O_2} \) to \( \mathrm{-2} \) in \( \mathrm{H_2O} \)) and simultaneously oxidized (from \( \mathrm{-1} \) to \( \mathrm{0} \) in \( \mathrm{O_2} \)). Hence, it is a redox reaction.