NCERT Solutions for Class 7 Science Chapter 6 Physical and Chemical Changes

Edited By Vishal kumar | Updated on Feb 16, 2024 06:03 PM IST

Many changes happen in this world as time passes. These changes are of different types. Class 7 NCERT Science explains some physical and chemical changes around us. The NCERT solutions of Class 7 Science Chapter 6 Physical and Chemical Changes help in familiarising with the concepts studied in the chapter. There are 12 questions in the exercise. All these questions are discussed in the NCERT solutions for Class 7 Science chapter 6 Physical and Chemical Changes.

This Story also Contains

NCERT Solutions for Class 7 Science Chapter 6 – Physical and Chemical Changes
NCERT Solutions for Class 7 Science Chapter 6 Physical And Chemical Changes: Exercise Solutions
Chapterwise NCERT Solutions of Class 7 Science
Physical And Chemical Changes Class 7 Chapter 6-Topics
Key Features of Class 7 Physical and Chemical Changes NCERT Solutions

The changes in shape, size colour or state are physical changes. When one or more new substances are formed during a change then the changes are chemical changes. To understand both physical and chemical changes there are different interesting activities mentioned in the NCERT Class 7 Science chapter 6. Along with these activities, practising the NCERT solutions for Class 7 Science Chapter 6 Physical and Chemical Changes can make your learning better. You can get NCERT Solutions from Classes 6 to 12 for Science and Maths by clicking on the above link. Students are recommended to go through NCERT Solutions for Class 7 to score high marks in their examinations.

**As per the CBSE Syllabus 2023-24, this chapter has been renumbered as Chapter 5 in Class 7 Science.

Free download physical and chemical changes class 7 solutions PDF for CBSE exam.

NCERT Solutions for Class 7 Science Chapter 6 – Physical and Chemical Changes

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NCERT Solutions for Class 7 Science Chapter 6 Physical And Chemical Changes: Exercise Solutions

1. Classify the changes involved in the following processes as physical or chemical changes:

(a) Photosynthesis

Answer:

(a) Photosynthesis is a chemical change.

1. Classify the changes involved in the following processes as physical or chemical changes:

(b) Dissolving sugar in water

Answer:

(b) Dissolving sugar in water is a physical change.

1. Classify the changes involved in the following processes as physical or chemical changes:

(c) Burning of coal

Answer:

(c) Burning of coal is a chemical change.

1. Classify the changes involved in the following processes as physical or chemical changes:

(d) Melting of wax

Answer:

(d) Melting of wax is a physical change.

1. Classify the changes involved in the following processes as physical or chemical changes:

(e) Beating aluminium to make aluminium foil

Answer:

(e) Beating aluminium to make aluminium foil is a physical change.

1. Classify the changes involved in the following processes as physical or chemical changes:

(f ) Digestion of food

Answer:

Digestion of food is a chemical change.

During digestion, enzymes in the stomach and intestines break down food molecules into simpler molecules.

2. State whether the following statements are true or false. In case a statement is false, write the corrected statement in your notebook.

(a) Cutting a log of wood into pieces is a chemical change. (True/False)

(b) Formation of manure from leaves is a physical change. (True/False)

(c) Iron pipes coated with zinc do not get rusted easily. (True/False)

(d) Iron and rust are the same substances. (True/False)

(e) Condensation of steam is not a chemical change. (True/False)

Answer:

(a) False because cutting a log of wood into pieces is a physical change.

(b) False because the formation of manure from leaves is a chemical change.

(d) False because Iron and rust are different substances.

(e) True

3. Fill in the blanks in the following statements:

(a) When carbon dioxide is passed through lime water, it turns milky due to the formation of _________.

(b) The chemical name of baking soda is _________.

(c) Two methods by which rusting of iron can be prevented are _________ and _________.

(d) Changes in which only _________ properties of a substance change are called physical changes.

(e) Changes in which new substances are formed are called _________ changes.

Answer:

(a) When carbon dioxide is passed through lime water, it turns milky due to the formation of calcium carbonate.

(b) The chemical name of baking soda is sodium hydrogen carbonate.

(c) Two methods by which rusting of iron can be prevented are galvanization and painting.

(d) Changes in which only physical properties of a substance change are called physical changes.

(e) Changes in which new substances are formed are called chemical changes.

4. When baking soda is mixed with lemon juice, bubbles are formed with the evolution of a gas. What type of change is it? Explain.

Answer:

When baking soda is mixed with lemon juice then it is a chemical change, bubbles are formed with the evolution of a carbon dioxide gas.

5. When a candle burns, both physical and chemical changes take place. Identify these changes. Give another example of a familiar process in which both the chemical and physical changes take place.

Answer:

When a candle burns, both physical and chemical changes take place. On heating, candle wax gets melted is a physical change since it again turns into wax on cooling.

The wax gives carbon dioxide, heat, light, water vapour and carbon soot on heating with states chemical change.

Another example is the lightening of the bulb using a dry cell.

6. How would you show that setting of curd is a chemical change?

Answer:

The setting of curd is a chemical change because the new substance(curd) formed from milk differs in taste and it cannot be converted into milk again i.e. it is irreversible.

7. Explain why burning of wood and cutting it into small pieces are considered as two different types of changes.

Answer:

The burning of wood is a chemical change because wood after burning gives carbon dioxide, ash, heat, water vapour also it is an irreversible process.

Whereas cutting wood into small pieces is a physical change because the original composition of wood remains the same and no new substance is formed.

8. Describe how crystals of copper sulphate are prepared.

Answer:

The crystals of copper sulphate are prepared as follows:

1. A cup of water is taken in a beaker.

2. Add some drops of dilute sulphuric acid in it.

3. Heat it and when it starts boiling add copper sulphate powder slowly with continuous stirring.

4. The copper sulphate powder is added till the saturation level.

5. Filter the solution and cool it.

6. Leave it undisturbed and we will observe copper sulphate crystals after some hours.

9. Explain how painting of an iron gate prevents it from rusting.

Answer:

Painting of an iron gate prevents direct contact of iron with water and air(oxygen) which are required for rusting.

No exposure of water and oxygen with iron prevents iron from rusting.

10. Explain why rusting of iron objects is faster in coastal areas than in deserts.

Answer:

Rusting occurs with direct contact of iron with water and oxygen.

In coastal areas,the moisture content is high in the air which states rusting of iron objects is faster in coastal areas because in deserts moisture in the air is absent.

11. The gas we use in the kitchen is called liquified petroleum gas (LPG). In the cylinder it exist as a liquid. When it comes out from the cylinder it becomes a gas (Change – A) then it burns (Change – B). The following statements pertain to these changes. Choose the correct one.

(i) Process – A is a chemical change.

(ii) Process – B is a chemical change.

(iii) Both processes A and B are chemical changes.

(iv) None of these processes is a chemical change.

Answer:

The gas we use in the kitchen is called liquified petroleum gas (LPG). In the cylinder, it exists as a liquid. When it comes out from the cylinder it becomes a gas (Change – A) then it burns (Change – B). This is a chemical change.

Thus, option (ii) is correct.

12. Anaerobic bacteria digest animal waste and produce biogas (Change – A). The biogas is then burnt as fuel (Change – B). The following statements pertain to these changes. Choose the correct one.

(i) Process – A is a chemical change.

(ii) Process – B is a chemical change.

(iii) Both processes A and B are chemical changes.

(iv) None of these processes is a chemical change.

Answer:

Anaerobic bacteria digest animal waste and produce biogas (Change – A). The biogas is then burnt as fuel (Change – B).

Both process A and B are a chemical change.

Thus, option (iii) is correct.

Class 7 science chapter 6 question answer hold substantial importance in a student's science education. These solutions provide a foundational understanding of the distinctions between physical and chemical changes in matter, which is fundamental in chemistry. Furthermore, the practical relevance of these concepts in daily life, coupled with their significance as a prerequisite for advanced chemistry studies, makes this class 7 science chapter 6 ncert solutions essential. It also fosters problem-solving skills and prepares students for examinations, making it a crucial component of their science curriculum. In terms of difficulty, the chapter's concepts are explained comprehensively in the class 7 physical and chemical changes ncert solutions, making it accessible and enabling students to grasp the content effectively.

Chapterwise NCERT Solutions of Class 7 Science

Chapter 1	Nutrition in Plants
Chapter 2	Nutrition in Animals
Chapter 3	Fibre to Fabric
Chapter 4	Heat
Chapter 5	Acids, Bases and Salts
Chapter 6	Physical and Chemical Changes
Chapter 7	Weather, Climate and Adaptations of Animals to Climate
Chapter 8	Winds, storms and cyclones
Chapter 9	Soil
Chapter 10	Respiration in Organisms
Chapter 11	Transportation in Animals and Plants
Chapter 12	Reproduction in Plants
Chapter 13	Motion and Time
Chapter 14	Electric Current and its Effects
Chapter 15	Light
Chapter 16	Water: A Precious Resource
Chapter 17	Forests: Our Lifeline
Chapter 18	Wastewater Story

Physical And Chemical Changes Class 7 Chapter 6-Topics

Topics for physical and chemical changes class 7 questions and answers are given below:

Physical Changes
Chemical Change
Rusting Of Iron
Crystallisation

NCERT Solutions for Class 7 Subject Wise

NCERT Solutions for Class 7 Maths

NCERT Solutions for Class 7 Science

Important terms to be remembered :

The main terms to be memorised after going through the chapter and also NCERT solutions for Class 7 Science chapter 6 Physical and Chemical Changes are listed below.

Crystallisation: The process of forming large crystals of pure substances are known as crystallisation.
Rusting of iron: If iron is kept in moist air a brownish film is formed on the iron. The brownish substance is called rust and the process is called rusting.
Galvanisation: In the NCERT Class 7 book the given definition is- Galvanisation is the process of depositing a layer of zinc on iron. Galvanisation prevents iron from rusting.

Key Features of Class 7 Physical and Chemical Changes NCERT Solutions

Comprehensive Coverage: The physical and chemical changes class 7 solutions cover all topics and concepts related to physical and chemical changes, ensuring a thorough understanding of the chapter.
Clear Explanations: The physical and chemical changes class 7 ncert solutions provide clear and concise explanations, making complex concepts easy to grasp for students.
Step-by-Step Approach: They follow a step-by-step approach, breaking down class 7 science chapter 6 question answer and problem-solving processes into manageable steps.
Illustrations and Examples: The class 7 science chapter 6 ncert solutions include illustrations and examples to aid in visualization and better comprehension of concepts.
Relevance: The class 7 physical and chemical changes ncert solutions highlight the practical relevance of physical and chemical changes in daily life, fostering a deeper connection to the subject matter.
Exam-Oriented: They are designed to assist students in preparing for examinations, with physical and chemical changes class 7 questions and answers to typical questions that may appear in tests and exams.
Language Clarity: The language used in the solutions is student-friendly, ensuring that students can follow along and learn independently.
Accessible: The class 7 science ch 6 question answer are readily available in printed and digital formats, making them easily accessible to all students.
Alignment with NCERT Curriculum: The science chapter 6 class 7 solutions are closely aligned with the NCERT curriculum, ensuring consistency with what is taught in classrooms.

These features collectively make Class 7 NCERT solutions for "Physical and Chemical Changes" an invaluable resource for students to master the chapter effectively.

Also Check NCERT Books and NCERT Syllabus here

Frequently Asked Questions (FAQs)

1. Is the Class 7 Science Chapter 6 Physical and Chemical Changes is useful in higher studies ?

Yes, this chapter is very important for higher studies in the field of science and Chemistry. Physical and Chemical Changes is Studied in Class 9 NCERT Syllabus

2. Classify the changes.

Changes can be classified into the following five categories.

Reversible and Irreversible Changes
Slow and Fast changes
Natural and Man-made Changes
Periodic and Non-Periodic Changes
Physical and Chemical Changes

3. What are the topics covered in NCERT Class 7 Science Chapter 6?

Here are the topics covered in NCERT Class 7 Science chapter 6

Physical Changes
Chemical Change
Rusting Of Iron
Crystallisation

Also Read

NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story

NCERT Solutions for Class 7 Science Chapter 17 Forests Our Lifeline

NCERT Solutions for Class 7 Science Chapter 16 Water A Precious Resource

NCERT Solutions for Class 7 Science Chapter 14 Electric Current and Its Effects

NCERT Solutions for Class 7 Science Chapter 13 Motion and Time

NCERT Solutions for Class 7 Science Chapter 12 Reproduction in Plants

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Option 1) decrease twice	Option 2) increase two fold
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