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Important Questions for CBSE Class 7 Science Chapter 5 - Physical and Chemical Changes

CBSE

Class 7 Important Question

Science

Chapter 6: Physical And Chemical Changes

CBSE Class 7 Science Chapter-5 Important Questions - Free PDF Download

Free PDF download of Important Questions with solutions for CBSE Class 7 Science Chapter 5 - Physical and Chemical Changes prepared by expert Science teachers from the latest edition of CBSE (NCERT) books is available here. Register Online for NCERT Solutions Class 7 Science tuition on Vedantu.com to score more marks in the CBSE board examination.

Vedantu is a platform that provides free CBSE Solutions (NCERT) and other study materials for students. Maths students who are looking for better solutions can download Class 7 Maths NCERT Solutions to help you to revise the complete syllabus and score more marks in your examinations.

Topics Covered in Chapter 5 Physical and Chemical Changes of CBSE Class 7 Science

Physical change
Chemical change
Rusting of iron
Crystallisation

Study Important Questions for Class 7 Science Chapter 5 – Physical and Chemical Changes

Very Short Answer Questions (1 Mark)

1. Identify the following changes as physical or chemical.

a. Dissolving sugar in water.

Ans: Physical.

b. Formation of rain from clouds.

Ans: Physical.

c. Formation of acid rain

Ans: Chemical.

d. Combustion

Ans: Chemical.

e. Hammering a nail flat.

Ans: Physical.

Short Answer Questions (3 Marks)

2. What are physical properties? Give examples.

Ans: Physical characteristics are features of a substance that may be determined based on its appearance.

Examples: shape, size, colour, state of compound etc.

3. What are chemical changes? Give examples.

Ans: When one or more compounds react to generate completely new products, this is referred to as a chemical change. The original reactant or substance changes totally as a result of a chemical transformation. The final product is unique. The transformation is irreversible.

Examples: Combustion, corrosion, photosynthesis etc.

4. What are physical changes? Give examples.

Ans: Physical changes occur in a matter that does not result in the creation of a new product. During these transitions, the matter often shifts from one state to another. For example, changes in the state of matter, the solubility of salt and sugar in water, and so on.

5. Explain how burning a strip of magnesium ribbon is a chemical change.

Ans: When magnesium ribbon is burned in the presence of air, it produces white ash with a dazzling white light which is known as magnesium oxide. The ashes formed look physically different in appearance from the initial reactant. It is a chemically unique matter at the same time. Burning magnesium ribbon is an example of a chemical shift because the product is an entirely different compound.

6. What happens when vinegar is added to baking soda? How do you test the gas produced?

Ans: Vinegar is acidic in nature on the other hand baking soda is basic in nature. When we combine these two salts, water along with carbon dioxide gas is formed.

The gas produced is passed through lime water. The lime turns milky or white due to the formation of calcium carbonate. This test confirms the presence of carbon dioxide.

Long Answer Questions (5 Marks)

7. What are the indications of a chemical change?

Ans: The following signs of chemical change are present:

Heat may be absorbed or released in the reaction.
There might be the production of sound during or at the end of the reaction.
A pleasant or pungent odour is created.
A change in the colour of the solution may occur.
Formation of gas.

8. Explain the formation of rust.

Ans: The degrading of metals such as iron in response to the environment is known as rusting. When it comes to oxygen and water, iron is extremely reactive. The production of iron oxide from iron is referred to as rust. It causes the iron article to deteriorate. Rust (Iron III oxide) is formed when iron combines with oxygen and water. Rust starts on the surface and works its way deeper into the metal.

Iron (Fe) + Oxygen (O₂) (from the air) + water (H2O) rust (iron oxide Fe2O3)

9. How can rusting of iron be prevented? Suggest and explain any three methods.

Ans: Rusting is a phenomenon that occurs on the surface of a metal. It can be avoided in the following ways:

Applying oil or grease on the surface inhibits the iron surface from coming into touch with the atmosphere, which prevents rusting.
Galvanization: A layer of a more reactive metal, such as zinc, is deposited on the surface of iron to protect it from rust.
Painting: Applying a layer of paint to the metal's surface stops it from coming into contact with the atmosphere once more.
Alloying: To make alloys, iron can be combined with other metals and non-metals. Rust resistance is a feature of alloys. Stainless steel is an important iron alloy.

Benefits of Referring to the Important Questions of Class 7 - Physical and Chemical Changes

Students must go through the important questions of each chapter of Science, but why? Some of the reasons for this have been listed below:

These questions help you to evaluate your knowledge and understanding of any particular chapter.
If you refer to other questions that are not given in your NCERT book, then you will prepare yourself for the examination paper where the teacher might ask you some tricky questions.
It also helps you to understand the topic in depth.
These notes are error-free and adhere to the CBSE standards.
It helps students' thinking ability and problem-solving abilities, which help students to secure good marks not in the current class, but in all academic sessions.

These notes are prepared by expert and experienced Science teachers and subject matter experts having in-depth knowledge of the topics covered in this chapter.
These notes are error-free and adhere to the CBSE standards. Hence, students can reliably refer to these notes while preparing for their exams.
With these notes, students can evaluate their understanding of the chapter and find the loopholes, if any.
These notes follow the latest syllabus prescribed by the CBSE and cover important questions in Chapter 12 of the NCERT book.
Students can easily download the PDF at no cost and study them offline too.

Students can also download the PDF of solutions for NCERT exercises in Science and other subjects. They can also access other study material from our website free of cost. We hope all the students find the study material useful for their preparation and score well in the exams.

NCERT Class 7 Science Chapter wise Solutions

Importances about Important Questions for CBSE Class 7 Sciences Chapter 5- Physical and Chemical Changes

The importance of "Important Questions for CBSE Class 7 Science Chapter 5 - Physical and Chemical Changes" lies in their role as a strategic learning tool. This chapter delves into the fundamental concepts of chemistry, distinguishing between physical and chemical changes in matter. These important questions serve as a targeted and efficient means of revision, helping students reinforce their understanding of the chapter's key principles.

Moreover, they prepare students comprehensively for examinations by covering a wide range of topics and question types, similar to what they might encounter in tests and assessments. By tackling these questions, students not only assess their knowledge but also develop problem-solving skills, critical thinking, and analytical abilities.

Furthermore, these questions encourage practical application of chemistry principles in real-world scenarios, fostering an appreciation for the relevance of science in daily life. In essence, these important questions empower students to excel academically while nurturing their scientific curiosity and understanding of the dynamic world of chemistry.

Conclusion

"Important Questions for CBSE Class 7 Science Chapter 5 - Physical and Chemical Changes" are a valuable resource that holds immense significance in a student's scientific education. This chapter explores the intriguing realm of chemistry by distinguishing between physical and chemical changes in matter. The importance of these questions lies in their ability to serve as a comprehensive revision aid, consolidating students' understanding of essential scientific principles. They play a pivotal role in exam preparation, offering a diverse range of question types that mirror what students may encounter in assessments. Furthermore, these questions foster critical thinking and problem-solving skills, instilling a deeper appreciation for the practical relevance of chemistry in our daily lives. Overall, they empower students to excel academically while nurturing their curiosity about the ever-evolving world of science.

FAQs on Important Questions for CBSE Class 7 Science Chapter 5 - Physical and Chemical Changes

1. How many questions are present in Chapter 5 of Class 7 Science?

In the textbook, questions are given at the end of each chapter. Writing answers to these questions help you to gauge your level of understanding of the concept taught. At the same time, it also encourages you to think and recall. All of these skills will be required in every exam that you write. There are 12 questions given at the end of Chapter 5 of Class 7. Extra four questions are given for the purpose of extended learning.

2. What are the important topics in the Chapter 5 of NCERT Solutions for Class 7 Science?

Chapter 5 of Class 7 explains the difference between physical and chemical changes. We come across several of these changes but we can hardly notice them. It is important to understand the concepts of physical and chemical changes and the difference between them. It is also crucial that you memorize some of the equations that you can cite as examples in the exam. Understand the process of rusting, galvanization and crystallization. Make short notes on them. They will come in handy.

3. Explain the process of rusting with the help of an equation.

Iron is a meal that is of immense significance. Discovery of iron thousands of years back has revolutionized our way of life. Iron is present in the house we live in, buildings we work or study in, the cars we travel in and our highways and airplanes. Oxygen and water present in the environment reacts with the iron. When the moisture in the air is high, rusting gathers pace. The process of rusting can also be explained by the equation: Iron + Oxygen + Water -> Rusting.

4. What is galvanisation and why is it needed?

Galvanization is the process in which a layer of zinc is deposited on iron to prevent it from rusting. A layer of zinc prevents the molecules of oxygen and water from coming in contact with the iron. One can also apply paint or grease. Galvanization is needed because iron is an important part of all of our infrastructures. Rusting destroys the quality of the infrastructure and also weakens it. Rusting causes monetary loss as a huge amount of money is invested in buildings, houses, highways, etc.

5. Do I have to practice questions of Chapter 5 Class 7 Science?

Chapter 5 of Class 7 introduces you to the concept of physical and chemical changes. The concept forms the basis of your higher classes. You will be introduced to several concepts in-depth in your higher classes that will be building upon this chapter’s foundation. Practising questions given in the textbook helps you to analyze how well you have understood the concept. The more questions you practice, the more your understanding will be consolidated. Do not cram the information given. Understand the basics and then practice the questions and revise.