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Science (086) — AI-generated practice question

AI-generated practice question — model-generated for extra practice, not a previous-year CBSE board question.

Q1. [1] straightforward exam-ready
The reaction CaO(s) + H₂O(l) → Ca(OH)₂(aq) + Heat is an example of: (A) Decomposition reaction (B) Displacement reaction (C) Combination reaction (D) Double displacement reaction
  1. A Decomposition reaction
  2. B Displacement reaction
  3. C Combination reaction
  4. D Double displacement reaction
Generated by claude-sonnet-4-6 · 2026-06-26 00:53 · grounding rag
Model Answer

(C) Combination reaction

In this reaction, two reactants (CaO and H₂O) combine to form a single product Ca(OH)₂, which is the definition of a combination reaction.

Source: Chapter 1, Section 1.2.1 Combination Reaction

Explanation

The key indicator here is one product formed from two reactants. The textbook directly uses this equation as the example for combination reactions. Also note it is exothermic (releases heat), but that does not change its classification as a combination reaction. Eliminate other options: no single substance breaks down (not decomposition), no element replaces another (not displacement), and no ion exchange occurs (not double displacement).

Previous-year CBSE Grade 10 board exam questions, organised by subject and chapter, each with a model answer — free to read and print.