Question 281 markMCQSection B

Read the following statements: I. When a red litmus paper is dipped into reaction mixture of a saponification reaction, it turns blue and the reaction is exothermic. II. When a blue litmus paper is dipped into reaction mixture of a saponification reaction, its colour does not change and the reaction is exothermic. III. When a red litmus paper is dipped into reaction mixture of a saponification reaction, its colour does not change and the reaction is endothermic. IV. When a blue litmus paper is dipped into reaction mixture of a saponification reaction, its colour does not change and the reaction is endothermic. Which of the above statements are correct:

Chemical Reactions and Equations
Saponification Reaction

Options

(A)I and II
(B)II and III
(C)III and IV
(D)I and IV

Official answer

Option A is correct (I and II).

Answer keywords:saponificationexothermicbasicred litmus turns bluesodium hydroxidesoap

Marking scheme

  1. 1.1 Mark for selecting the correct option A.

Hint

Recall that saponification involves a strong alkali (NaOHNaOH) and releases heat during the formation of soap.

Quick oral answer

Saponification is an exothermic reaction that produces a basic mixture. Consequently, it releases heat and turns red litmus paper blue.

Common mistakes

  1. 1.Thinking saponification is endothermic because heat is sometimes applied initially to start the reaction.
  2. 2.Confusing the basic nature of soap with an acidic nature.

Analysis and explanation

Saponification is the alkaline hydrolysis of fats or oils using a strong base like sodium hydroxide (NaOHNaOH) to produce soap and glycerol.


  • Nature of the reaction mixture: Because a strong base (NaOHNaOH) is used as a reactant, and soap itself is a salt of a strong base and weak fatty acid, the reaction mixture is highly basic (alkaline). Therefore, it turns red litmus paper blue (Statement I is correct) and has no effect on blue litmus paper (Statement II is correct).
  • Thermal nature of the reaction: Saponification is an exothermic chemical reaction, meaning it releases heat energy to the surroundings, making the reaction mixture warm.

Since Statements I and II are correct, Option A is the correct choice.

Interesting facts

The term 'saponification' literally means 'soap-making' and comes from the Latin word 'sapo', which means soap.

Question details

Q28 of 40 questions

Board
CBSE
Class
Class 10
Subject
Science
Year
2013
Section
Section B
Marks
1
Type
MCQ
Chapter
Chemical Reactions and Equations
Topic
Saponification Reaction
Bloom's level
Understanding
Syllabus topic
Types of chemical reactions: exothermic reactions, practical skills

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Frequently asked questions

How many marks does this question carry in CBSE Class 10 Science 2013?

This question carries 1 mark in the CBSE Class 10 Science 2013 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 "Saponification Reaction" from CBSE Class 10 Science.

What type of question is this in the CBSE Class 10 Science 2013 paper?

This is a MCQ question from Section B in the CBSE Class 10 Science 2013 paper.