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Q77 (NDA-I/2021) Science & Technology › Basic Science (Physics, Chemistry, Biology) › Basic chemical principles Answer Verified

Reaction of ick lime (CaO) with water to produce slaked lime (Ca(OH)2) is an example of

Result
Your answer: —  Â·  Correct: D
Explanation

The reaction of quicklime (calcium oxide, CaO) with water to produce slaked lime (calcium hydroxide, Ca(OH)2) is a classic example of an exothermic reaction. During this process, calcium oxide reacts vigorously with water, releasing a significant amount of heat that makes the reaction mixture warm and can even produce steam [2]. In chemical terms, reactions that release heat into the surroundings are classified as exothermic. Additionally, this specific reaction is a combination reaction because two reactants (CaO and H2O) combine to form a single product, Ca(OH)2 [2]. It is not a displacement or decomposition reaction, as the latter would involve breaking down a compound into simpler substances, such as the thermal decomposition of limestone into quicklime [3]. Therefore, the evolution of heat confirms it is an exothermic reaction [1].

Sources

  1. [1] Science , class X (NCERT 2025 ed.) > Chapter 1: Chemical Reactions and Equations > Figure 1.3 > p. 6
  2. [2] Science , class X (NCERT 2025 ed.) > Chapter 1: Chemical Reactions and Equations > QUESTIONS > p. 7
  3. [3] https://www.sciencedirect.com/topics/engineering/lime-cycle
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SIMILAR QUESTIONS

CAPF · 2022 · Q39 Relevance score: 5.86

Calcium oxide reacts with water to produce slaked lime. It is an example of

CDS-I · 2023 · Q52 Relevance score: 3.33

Which of the following statements with regard to the reaction given below are correct? CaO(s) + H2O(l) → Ca(OH)2 (aq) + Heat 1. Quicklime is used for white-washing of walls. 2. The solution of slaked lime is used for whitewashing of walls. 3. CaO reacts slowly with CO2 in air to form a thin layer of CaCO3 on walls. 4. Calcium hydroxide called 'slaked lime' is an inorganic compound. Select the correct answer using the code given below.

CDS-II · 2023 · Q52 Relevance score: 2.86

During white-washing of walls, slaked lime reacts slowly with carbon dioxide in air to form a thin layer of calcium carbonate on the walls. Which of the following reactions represents this correctly?

NDA-II · 2025 · Q96 Relevance score: 2.36

The reaction that occurs on passing carbon dioxide gas through lime water is