Question 212 marksVery Short AnswerSection B

$Name the type of chemical reaction in which calcium oxide reacts with water. Justify your answer by giving balanced chemical equation for the chemical reaction.$

Q: Name the type of chemical reaction in which calcium oxide reacts with water. Justify your answer by giving balanced chemical equation for the chemical reaction.

The reaction between calcium oxide and water is a **Combination Reaction**. It is also characterized as an **Exothermic Reaction** because a large amount of heat is evolved during the process. **Justification:** In this reaction, two reactants (Calcium oxide and Water) combine to form a single product (Calcium hydroxide). **Balanced Chemical Equation:** $$CaO(s) + H_2O(l) \rightarrow Ca(OH)_2(aq) + \text{Heat}$$

Chemical Reactions and Equations

Combination Reaction

Official answer

CaO(s) + H_2O(l) \rightarrow Ca(OH)_2(aq) + \text{Heat}

Combination Reaction

Exothermic

Calcium oxide

Calcium hydroxide

Single product

Marking scheme

1. $1 mark for identifying 'Combination Reaction'.$
2. $1 mark for the correct balanced chemical equation with state symbols.$

Hint

$Recall Activity 1.4 where quick lime is added to water. How many products are formed?$

Quick oral answer

$This is a combination reaction. Calcium oxide (quick lime) reacts with water to form calcium hydroxide (slaked lime), and the reaction is highly exothermic.$

Common mistakes

1. $CaOH$
2. $Forgetting to mention that heat is released.$

Analysis and explanation

According to the NCERT text (Activity 1.4), calcium oxide (quick lime) reacts vigorously with water. This is a classic example of a combination reaction because the definition states: 'Such a reaction in which a single product is formed from two or more reactants is known as a combination reaction.' Additionally, the release of heat makes it an exothermic chemical reaction.

Interesting facts

$The reaction of quick lime with water was historically used to produce light in theaters (limelight) before electric lighting was invented.$

Question details

Q21 of 39 questions

Board: CBSE
Class: Class 10
Subject: Science
Year: 2024
Section: Section B
Marks: 2
Type: Very Short Answer
Chapter: Chemical Reactions and Equations
Topic: $Combination Reaction$
Bloom's level: Applying
Syllabus topic: $Types of Chemical Reactions: Combination Reaction$

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Frequently asked questions

$How many marks does this question carry in CBSE Class 10 Science 2024?$

$This question carries 2 marks in the CBSE Class 10 Science 2024 examination.$

$Which chapter does this question come from in Science?$

$This question is from the chapter "Chemical Reactions and Equations" in the CBSE Class 10 Science syllabus.$

$What topic does this question cover in Science?$

$This question covers the topic "Combination Reaction" from CBSE Class 10 Science.$

$What type of question is this in the CBSE Class 10 Science 2024 paper?$

$This is a Very Short Answer question from Section B in the CBSE Class 10 Science 2024 paper.$