Which one of the following reactions is an example of decomposition reaction?

A decomposition reaction is a chemical process where a single reactant breaks down into two or more simpler products [3]. This type of reaction typically requires energy in the form of heat, light, or electricity to break the chemical bonds [3]. Option 2, the reaction of silver chloride (AgCl) in the presence of sunlight, is a classic example of photolytic or photochemical decomposition. In this reaction, white silver chloride absorbs light energy and decomposes into grey silver metal and chlorine gas [4]. In contrast, Option 1 is a combustion reaction, Option 3 is a redox reaction involving reduction of copper oxide, and Option 4 is a single displacement reaction where iron displaces copper from copper sulfate [3]. Therefore, only the breakdown of AgCl fits the criteria of a decomposition reaction.

Sources

1. [3] Science , class X (NCERT 2025 ed.) > Chapter 1: Chemical Reactions and Equations > What you have learnt > p. 14
2. [1] Science , class X (NCERT 2025 ed.) > Chapter 1: Chemical Reactions and Equations > Activity 1.8 > p. 10
3. [4] Science , class X (NCERT 2025 ed.) > Chapter 1: Chemical Reactions and Equations > Activity 1.8 > p. 9
4. [2] Science , class X (NCERT 2025 ed.) > Chapter 1: Chemical Reactions and Equations > CuO +H Cu+H O 2 2 → Heat (1.29) > p. 12