CBSE Class 6 Science Chapter 6: Changes Around Us NCERT Solutions

Reviewed by NCERT Help Editorial Team · Updated on 29 Jul 2026

NCERT Solutions PDF Class 6 PDF

This chapter delves into the fundamental concept of changes that occur in our surroundings. The NCERT Solutions for Class 6 Science, Chapter 6, 'Changes Around Us,' provide clear explanations and examples of both reversible and irreversible changes. Students will learn to identify different types of changes, such as folding clothes, melting ice, cooking food, and ripening of fruits, and classify them based on their reversibility. The solutions offer step-by-step guidance to understand the underlying principles, helping students grasp how some changes can be undone while others cannot. This resource is designed to aid in understanding the scientific basis of everyday transformations and is an excellent tool for exam preparation and revision.

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Quick info

Board	CBSE
Class	Class 6
Subject	Science
Session	2026
Language	English
Type	NCERT Solutions
Chapter	Chapter 6

Chapter summary

Chapter 6, 'Changes Around Us,' focuses on distinguishing between reversible and irreversible changes. The NCERT Solutions cover exercises that require students to identify and classify various everyday changes. Key concepts include understanding that some changes can be undone (reversible) by simple physical means, while others result in a new substance and cannot be easily reversed (irreversible). The solutions explain examples like folding clothes versus cooking food, helping students build a foundational understanding of chemical and physical changes.

Learning outcomes

Understand the concept of changes around us.
Differentiate between reversible and irreversible changes.
Identify examples of reversible changes in daily life.
Identify examples of irreversible changes in daily life.
Explain why certain changes are reversible or irreversible.

Topics covered

Paper topics

Changes Around Us
Reversible Changes
Irreversible Changes
Physical Changes
Chemical Changes
Examples of Reversible Changes
Examples of Irreversible Changes
Folding clothes
Melting ice
Cooking food
Ripening of fruits
Plaster of Paris hardening

Important topics

Distinguishing between reversible and irreversible changes
Identifying everyday examples of both types of changes
Understanding the nature of changes in cooking and ripening
The process of Plaster of Paris hardening

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Questions and Solutions

Question 1

To walk through a waterlogged area, you usually shorten the length of your dress by folding it. Can this change be reversed?

Solution: Yes, this change can be reversed. By unfolding the folded part of the dress, it can be restored to its original length. This is an example of a reversible change because the material of the dress is not fundamentally altered.

Question 2

You accidentally dropped your favourite toy and broke it. This is a change you did not want. Can this change be reversed?

Solution: No, this change cannot be reversed. Once a toy is broken into pieces, it is not possible to join them back perfectly to restore the toy to its original condition. This is an example of an irreversible change.

Question 3

Some changes are listed in the following table. For each change, write in the blank column, whether the change can be reversed or not.

The sawing of a piece of wood
The melting of ice candy
Dissolving sugar in water
The cooking of food
The ripening of a mango
Souring of milk

Solution: Here is the table with the changes classified as reversible or not:

No. Change | Can be reversed (Yes/No)
The sawing of a piece of wood | No
The melting of ice candy | Yes
Dissolving sugar in water | Yes
The cooking of food | No
The ripening of a mango | No
Souring of milk | No

Explanation:

Sawing wood results in smaller pieces, which cannot be rejoined to form the original log.
Ice candy melts into water, but the water can be frozen again to form ice candy.
Sugar dissolves in water, but the water can be evaporated to get the sugar back.
Cooking food changes its properties permanently, making it irreversible.
A ripe mango cannot be turned back into an unripe mango.
Sour milk cannot be made fresh again.

Question 4

A drawing sheet changes when you draw a picture on it. Can you reverse this change?

Solution: It depends on how the picture is drawn. If the drawing is made with a pencil, the change can be reversed by erasing the drawing with an eraser. However, if the drawing is made with a pen, the ink soaks into the paper, and the change is generally irreversible.

Question 5

Give examples to explain the difference between changes that can or cannot be reversed.

Solution: The difference between reversible and irreversible changes can be explained with the following examples:

Examples of Reversible Changes:

Melting of Ice into Water: Ice melts to form water, and this water can be frozen again to obtain ice.
Folding a Paper: A paper can be folded to change its shape, but it can be unfolded to return to its original flat state.
Hot Milk to Cold Milk: Hot milk cools down, but it can be heated again to make it warm or hot.

Examples of Irreversible Changes:

Burning of a Candle: When a candle burns, it is consumed and turns into wax vapour and soot. This cannot be reversed to get the original candle back.
Bursting of Crackers: The chemical reactions during the bursting of crackers produce light, sound, and gases, which cannot be undone.
Cutting of Trees: A cut tree cannot be rejoined to grow back as a whole tree.

Question 6

A thick coating of a paste of Plaster of Paris (POP) is applied over the bandage on a fractured bone. It becomes hard on drying to keep the fractured bone immobilised. Can the change in POP be reversed?

Solution: No, the change in Plaster of Paris (POP) when it dries and becomes hard cannot be reversed easily. When water is mixed with POP, it undergoes a chemical reaction and sets into a hard solid. This is a chemical change where the composition of POP is altered, making it an irreversible process under normal conditions.

Question 7

A bag of cement lying in the open gets wet due to rain during the night. The next day the sun shines brightly. Do you think the changes, which have occurred in the cement, could be reversed?

Solution: No, the changes that have occurred in the cement cannot be reversed. When cement gets wet, it reacts with water and undergoes a chemical change, causing it to harden. This process is called setting of cement. Once cement has set, it cannot be turned back into its original powdery form.

Common mistakes

Confusing physical changes (like melting) with chemical changes (like cooking).
Assuming all changes involving a substance are irreversible.
Not considering the possibility of reversing a change under different conditions (e.g., drawing with pencil vs. pen).

Revision tips

Focus on classifying changes into reversible and irreversible categories.
Create your own list of everyday changes and try to classify them.
Pay close attention to the examples provided in the solutions for both types of changes.
Understand the reasoning behind why a change is irreversible (e.g., formation of a new substance).

Practice MCQs

Q1. Which of the following is an example of a reversible change?

Q2. When you fold your dress to walk through water, is this change reversible?

Q3. Which of these changes is irreversible?

Q4. If you draw a picture with a pencil on a drawing sheet, can this change be reversed?

Q5. What happens when Plaster of Paris (POP) paste dries on a fractured bone?

Frequently asked questions

What is the main focus of CBSE Class 6 Science Chapter 6?

Chapter 6, 'Changes Around Us,' focuses on helping students understand and differentiate between changes that can be reversed (reversible changes) and those that cannot be easily undone (irreversible changes).

What are some examples of reversible changes mentioned in the solutions?

Examples include folding clothes, melting of ice candy, dissolving sugar in water, and drawing with a pencil on a sheet, which can be undone by unfolding, freezing, evaporating the water, or erasing, respectively.

What are some examples of irreversible changes?

Irreversible changes include the sawing of wood, cooking of food, ripening of a mango, souring of milk, burning of a candle, bursting of crackers, and the hardening of cement or Plaster of Paris.

How do these NCERT Solutions help students?

These solutions provide clear, rewritten explanations for each question, helping students understand the concepts of reversible and irreversible changes with practical examples, which is crucial for their studies and exams.

Is drawing with a pen a reversible change?

No, drawing with a pen is generally considered an irreversible change because the ink cannot be easily removed from the paper without damaging it, unlike drawing with a pencil which can be erased.

What happens when cement gets wet?

When cement gets wet, it undergoes a chemical change and hardens. This change is irreversible, meaning the hardened cement cannot be turned back into its original powdery form.

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