NCERT Solutions For Class 7 Science Chapter 6 Physical And Chemical Changes

NCERT Solutions for Class 7 Science Chapter 6 – Free PDF Download

NCERT Solutions For Class 7 Science Chapter 6 Physical and Chemical Changes available in PDF. Students who want to score good marks in Class 7 examinations should solve the NCERT questions provided at the end of each chapter. Sometimes the NCERT Textbook questions are directly asked in the school examinations, which will be an added advantage for those students who practised the NCERT Solutions for Class 7.

Along with the NCERT Solutions for Class 7 Science, students can also find some important questions, revision notes and other facts about the different types of changes. The NCERT Solutions for Class 7 Science can be used for both class assignments, finals and also for Olympiad exams. By referring to these solutions students can attain a firm grip over the key concepts of Class 7 Science.

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

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Access Answers of NCERT Class 7 Science Chapter 6 – Physical and Chemical Changes

Exercise Questions

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

(a) Photosynthesis

(b) Dissolving sugar in water

(c) Burning of coal

(d) Melting of wax

(e) Beating aluminium to make aluminium foil

(f ) Digestion of food

Solution:

a) Chemical change

b) Physical Change

c) Chemical change

d) Physical Change

e) Physical Change

f) Chemical change

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)

Solution:

a) False

b) False

c) True

d) False

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.

Solution:

(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 painting and galvanization.

(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.

Solution:

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

Lemon juice + Baking soda → Carbon dioxide + other substances

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.

Solution:

Candle Burning

Physical change is melting of wax:

The chemical change is the burning of gas with the evolution of CO2

Digestion of Food

Physical change is the breakdown of larger food molecules to simpler ones

The chemical change is the digestion of food by the action of HCl and enzymes.

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

Solution:

The setting of curd is a chemical change because curd cannot be turned back to milk. The properties of milk and curd are different.

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

Solution:

Cutting of wood is a physical change as it does not change the nature of the wood. On the other hand, burning of wood is a chemical change as wood is converted to charcoal with the liberation of CO2.

8. Describe how crystals of copper sulphate are prepared.

Solution:

Crystals of copper sulphate are prepared using the crystallization method, which is described as follows

  • Take a cupful of water in a beaker.
  • Add a few drops of dilute sulphuric acid to this.
  • Heat the water and when it starts boiling, add copper sulphate powder while still stirring.
  • Add the copper sulphate powder till the solution becomes saturated. Filter into a china dish and allow it to cool.
  • The solution should be kept undisturbed. Slowly, the crystals of copper sulphate separate out.

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

Solution:

Rusting of iron requires contact with water (moisture) and oxygen. By painting an iron gate, we prevent the contact between iron, Oxygen and water (moisture), this helps in preventing rusting of iron.

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

Solution:

Rusting of iron requires contact with water (moisture) and oxygen. In coastal areas, humidity is more in comparision to that in deserts; hence, rusting of iron objects is faster in coastal areas than in deserts.

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

Solution:

The answer is (ii) Process – B is a chemical change.

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

Solution:

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

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

We all see different types of changes in our daily life activities, among which a few are reversible and few are irreversible. Some examples of these changes include melting of ice, a bud changing to a flower, melting of candle wax and a lot more. Based on their changes, they are classified into physical change and chemical change.

Physical change: A change that changes only the physical traits of the substance, without making any change in their internal structure. Examples of physical change include: boiling of water, chopping wood, dissolving sugar in water, crumpling of paper, melting an ice cube, etc.

Chemical change: A change that changes by affecting the internal structure of the substance to form a new substance. Examples of chemical change include: digesting food, burning wood, baking a cake, curdling of milk, mixing acid, boiling an egg, rusting of iron, etc.

Students can learn more in detail about these topics by referring to the NCERT Solutions for Class 7. These solutions come in handly during revisions and any doubt clearance.

Important topics covered in NCERT Solutions for Class 7 Science Chapter 6 Physical and Chemical Changes

  1. Physical Changes
  2. Chemical Changes
  3. Rusting of Iron
  4. Crystallisation

We, at BYJU’S, provide NCERT Solutions for all subjects and classes 1 to 12 in a chapter-wise format to help students in their studies. All the solutions in this study material are explained in a simple language and in an easy methodology for students to learn better and effectively. The NCERT Solutions for Class 7 Science Chapter 6 provide complete information regarding the topic along with the definitions and examples.

Further, the NCERT Solutions are available as PDFs and students can directly download these materials or can practise online, by visiting our website of BYJU’S.

Frequently Asked Questions on NCERT Solutions for Class 7 Science Chapter 6

How many questions are present in the Chapter 6 of NCERT Solutions for Class 7 Science?

About 12 questions are present in the Chapter 6 of NCERT Solutions for Class 7 Science. These questions include short answer questions and MCQs as per the latest NCERT textbook. The NCERT Solutions at BYJU’S can be referred to get a clear idea about the method of answering complex questions. The solutions are designed by experts after conducting a vast research on each concept. Students will be able to cross check their answers and get their doubts cleared by using the solutions PDF.

What are the important topics in the Chapter 6 of NCERT Solutions for Class 7 Science?

The important topics in the Chapter 6 of NCERT Solutions for Class 7 Science are –
1. Physical Changes
2. Chemical Changes
3.Rusting of Iron
4. Crystallisation
The concepts which are important from the exam point of view are explained in brief in the solutions. Each and every minute detail is covered as per the CBSE guidelines to help students ace the exam with much confidence.

What are physical and chemical changes discussed in the Chapter 6 of NCERT Solutions for Class 7 Science?

The changes in which physical properties of a substance change are physical changes whereas the changes in which new substances are formed are called chemical changes. Students are advised to refer to the NCERT Solutions to understand the crucial topics clearly. The solutions help to bridge the gap between the students and the subject which results in a better academic score. PDF format solutions are present in a chapter wise format which can be used by the students whenever required.

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