Which of the following decomposition reactions is NOT a redox reaction?
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. Decomposition of calcium carbonate.
The decomposition of calcium carbonate (CaCO₃) is not a redox reaction. In this reaction, calcium carbonate breaks down into calcium oxide (CaO) and carbon dioxide (CO₂) when heated. This process involves the breaking of chemical bonds but does not involve a change in the oxidation states of the elements involved. Both calcium and carbonate retain their oxidation states throughout the reaction. In contrast, redox reactions are characterized by the transfer of electrons, resulting in changes in oxidation states. Therefore, since there is no electron transfer in the decomposition of calcium carbonate, it is classified as a non-redox reaction.