Which one of the following is a decomposition reaction? a. 2so3 (g) → 2so2 (g) + o2 (g) b. ch4 (g) + 2o2 (g) → co2 (g) + 2h2o (g) c. 2lioh (s) + co2 (g) → li2co3 (s) + h2o (l) d. h2 (g) + cl2 (g) → 2hcl (g)

It would be A because Decomposition is when a substance breaks down into two. 

Answer;

A. 2SO3 (g) → 2SO2 (g) + O2 (g)

Explanation;A decomposition reaction is a type of chemical reaction where a single compound is broken down into two or more elements or new compounds.Decomposition reactions involve a single substance as a reactant and more than one substance as the product. Examples of decomposition reactions include the breakdown of hydrogen peroxide to water and oxygen, and the breakdown of water to hydrogen and oxygen.In the question above; the reaction; 2SO3 (g) → 2SO2 (g) + O2 (g) is an example of decomposition reaction.