Which one of the following when dissolved in H2O gives hissing sound

When water is added to quicklime (calcium oxide, CaO), a vigorous chemical reaction occurs, producing slaked lime (calcium hydroxide, Ca(OH)2) [c1, c3]. This process, known as the slaking of lime, is highly exothermic, meaning it releases a significant amount of heat energy [t4, t5]. The intense heat generated during this rapid hydration causes some of the water to instantly turn into steam, which escapes the mixture and produces a characteristic hissing sound [t3, t4]. This reaction is a classic example of a combination reaction where two reactants form a single product while evolving heat [c1, c4]. In contrast, limestone (calcium carbonate) is relatively insoluble and does not react vigorously with water, while slaked lime is the already-hydrated product of this reaction [t1, t5].

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 1: Chemical Reactions and Equations > Figure 1.3 > p. 6
2. [2] Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 8: Nature of Matter: Elements, Compounds, and Mixtures > Activity 8.1: Let us experiment > p. 118
3. [3] Science , class X (NCERT 2025 ed.) > Chapter 1: Chemical Reactions and Equations > QUESTIONS > p. 7