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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 initial-understanding
When calcium oxide is added to water, is heat released or absorbed? What type of reaction (in terms of energy) does this represent?
Generated by claude-sonnet-4-6 · 2026-06-26 00:53 · grounding rag
Model Answer

Heat is released. This represents an exothermic reaction, as heat is evolved along with the formation of the product (slaked lime).

Source: Chapter 1, Section 1.2.1 – Combination Reaction

Explanation

For a 1-mark question, examiners award the mark for correctly stating either that heat is released or that it is an exothermic reaction — ideally mention both in one line. The key term is exothermic; do not write "endothermic" (which is when energy is absorbed). The reaction CaO + H₂O → Ca(OH)₂ + Heat is the standard example of an exothermic combination reaction in this chapter.

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