Which one of the following reactions does not result in the evolution of hydrogen gas?

The evolution of hydrogen gas occurs in reactions where a reactive metal displaces hydrogen from an acid, base, or water. Zinc reacts with dilute sulphuric acid to form zinc sulphate and hydrogen gas [3]. Similarly, zinc reacts with sodium hydroxide solution to produce sodium zincate and hydrogen gas [2]. Potassium, being a highly reactive metal, reacts violently with water to produce potassium hydroxide and hydrogen gas [2]. In contrast, mixing water with Plaster of Paris (calcium sulphate hemihydrate) is a hydration reaction that forms gypsum (calcium sulphate dihydrate) [1]. This process is an exothermic physical-chemical change involving the setting of the material into a hard mass, but it does not involve the chemical reduction of hydrogen ions or the displacement of hydrogen atoms to form H2 gas [1].

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 1: Chemical Reactions and Equations > Figure 1.2 > p. 2
2. [3] https://www.sciencedirect.com/topics/nursing-and-health-professions/calcium-sulfate
3. [2] Science , class X (NCERT 2025 ed.) > Chapter 3: Metals and Non-metals > Activity 3.10 > p. 43