NCERT Solutions for Class 8 Science Chapter 8 Force and Pressure

Ever wondered what everything around you, your pencil, air, or even water, is made of? Let us find the answer through this chapter! The chapter Nature of Matter helps us understand the basic building blocks that make up everything around us. From the oxygen we breathe to the metal in your bicycle, everything is made up of matter. The matter is further classified into elements, compounds, and mixtures.

The important topics like pure substances, mixtures, and minerals are all discussed in this chapter, and the activities are also included to grasp the concepts better. The NCERT Solutions for Class 8 Science Chapter 8 Nature of Matter: Elements, Compounds, and Mixtures are designed by our experts in a systematic way to help you learn these concepts through a series of solved questions. These NCERT solutions will help you score well in exams and will improve your accuracy. We have also added some points that will help you build a good strategy to solve the questions.

NCERT Solutions for Class 8 Science Chapter 8: Download PDF

You can download the Science Class 8 Chapter 8 Nature of Matter: Elements, Compounds, and Mixtures solutions PDF from the icon below and access detailed solutions to all the questions present in the Class 8 NCERT textbook.

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NCERT Solutions for Class 8 Science Chapter 8 Exercise Questions

The Chapter 8 questions and answers are given below with simple explanations. The NCERT solutions for Class 8 Science Chapter 8 Nature of Matter: Elements, Compounds, and Mixtures are important from an exam point of view.

Keep The Curiosity Alive

Question 1. Consider the following reaction where two substances, A and B, combine to form a product C:

$A+B\to C$

Assume that A and B cannot be broken down into simpler substances by chemical reactions. Based on this information, which of the following statements is correct?

(i) $\mathrm{A},\mathrm{B}$, and C are all compounds and only C has a fixed composition.

(ii) C is a compound, and A and B have a fixed composition.

(iii) A and B are compounds, and C has a fixed composition.

(iv) A and B are elements, C is a compound and has a fixed composition.

Answer:

The correct answer is option (iv).

A and B cannot be broken into simpler substances; this means they are elements. C is a compound because it is made by chemically combining two elements (A and B) in a fixed ratio.

Question 2. Assertion: Air is a mixture.

Reason: A mixture is formed when two or more substances are mixed, without undergoing any chemical change.

(i) Both Assertion and Reason are true and Reason is the correct explanation for Assertion.

(ii) Both Assertion and Reason are true, but Reason is not the correct explanation for Assertion.

(iii) Assertion is true, but Reason is false.

(iv) Assertion is false, but Reason is true.

Answer:

The correct answer is option (i).

Air is a mixture because it consists of gases like nitrogen, oxygen, and carbon dioxide mixed together. These gases do not undergo a chemical reaction so the reason explains the assertion correctly.

Question 3. Water, a compound, has different properties compared to those of the elements oxygen and hydrogen from which it is formed. Justify this statement.

Answer:

Water is a compound formed by the chemical combination of hydrogen and oxygen. Even though hydrogen and oxygen are gases, water is a liquid with different properties such as boiling point, taste and color. These new properties result from the chemical bond formed between the elements which shows that a compound behaves differently from its elements.

Question 4. In which of the following cases are all the examples correctly matched? Give reasons in support of your answers.

(i) Elements - water, nitrogen, iron, air.

(ii) Uniform mixtures - minerals, seawater, bronze, air.

(iii) Pure substances - carbon dioxide, iron, oxygen, sugar.

(iv) Non-uniform mixtures - air, sand, brass, muddy water.

Answer:

The correct answer is option (iii).

The pure substances have a fixed composition and distinct properties. Carbon dioxide and sugar are compounds, while iron and oxygen are elements and all of them are pure. Water is not an element; it is a compound, so the first option is wrong. Air is a uniform mixture so the option (iv) is also incorrect.

Question 5. Iron reacts with moist air to form iron oxide, and magnesium burns in oxygen to form magnesium oxide. Classify all the substances involved in the above reactions as elements, compounds or mixtures, with justification.

Answer:

The reaction of iron will be written as

Iron + Oxygen + Water (moisture) → Iron oxide (rust)

For magnesium,

Magnesium + Oxygen $\to$ Magnesium oxide

So, iron and magnesium are elements, as they are made of only one kind of atom. But iron oxide and magnesium oxide are compounds as they are formed when elements react chemically with oxygen. These new substances have different properties than the elements they are made from.

Question 6. Classify the following as elements, compounds, or mixtures in Table 8.3. Carbon dioxide, sand, seawater, magnesium oxide, muddy water, aluminium, gold, oxygen, rust, iron sulfide, glucose, air, water, fruit juice, nitrogen, sodium chloride, sulfur, hydrogen, baking soda.

Identify pure substances amongst these and list them below

Answer:

Table 8.3

Pure substances have uniform and definite composition and properties. So, here the pure substances are carbon dioxide, iron, oxygen, glucose, aluminum, gold, water, nitrogen, sodium chloride, sulfur, hydrogen and magnesium oxide.

Question 7. What new substance is formed when a mixture of iron filings and sulfur powder is heated, and how is it different from the original mixture? Also, write the word equation for the reaction.

Answer:

When iron filings and sulfur powder are heated, they form iron sulfide which is a new compound.

Iron + Sulfur → Iron sulfide

It is different from the mixture because the compound (iron sulfide) has new properties and cannot be separated easily.

Question 8. Is it possible for a substance to be classified as both an element and a compound? Explain why or why not.

Answer:

No, a substance cannot be both an element and a compound at the same time. Elements contain only one type of atom, while compounds are made of two or more elements chemically combined. These are two different categories of matter based on their composition.

Question 9. How would our daily lives be changed if water were not a compound but a mixture of hydrogen and oxygen?

Answer:

If water were a mixture of oxygen and hydrogen then it would no longer have the same physical and chemical properties. It would be unsafe to drink or use, as hydrogen and oxygen gases do not combine naturally without a spark. Water would not have a fixed boiling point or freezing point like it does now as a compound.

Question 10. Analyze Fig. 8.24. Identify Gas A. Also, write the word equation of the chemical reaction.

Answer:

Here, in this experiment, the gas A is hydrogen. When a metal reacts with acid, it gives a salt with the evolution of hydrogen gas. In this experiment, zinc is a metal which reacts with the acid to give zinc chloride and hydrogen gas.

The equation is as follows-

Zinc + dilute hydrochloric acid $\to$ Zinc chloride + Hydrogen

Question 11. Write the names of any two compounds made only from non-metals, and also mention two uses of each of them.

Answer:

The two compounds that are made from non-metals only are carbon dioxide and sulfur dioxide.

Carbon dioxide $\left({\mathrm{CO}}_2\right)$

It is used in fire extinguishers.

It is used in cold drinks or soda water.

Sulfur dioxide $\left({\mathrm{SO}}_2\right)$

It is used as a preservative to prevent the staling of food.

It is used as a disinfectant to heal the wounds.

Question 12. How can gold be classified as both a mineral and a metal?

Answer:

Gold is found naturally in the Earth as a mineral in rocks. After extraction and purification, it becomes a shiny, soft metal used in jewelry and electronics. So, in nature, it is a mineral but in refined form, it is a metal.

Approach to Solve Chapter 8 Questions Effectively

To solve questions from Class 8 Science Chapter 8 Nature of Matter: Elements, Compounds, and Mixtures effectively, you need to work on the following points given below

1. Understand the key concepts first

Before attempting questions, make sure you clearly know the topics like

• What are elements, compounds, and mixtures?
• The differences between them (e.g., fixed composition, separation methods, and properties).
• Types of mixtures- homogeneous (uniform) and heterogeneous (non-uniform).

2. Identify the keywords in the question

Look for words like combined, separated, fixed composition, different properties, etc., as they will help you decide whether a substance is an element, compound, or mixture. You can learn these concepts by solving the Class 8 NCERT solutions.

3. Make notes

You can make use of tables to classify the elements, compounds, and mixtures. This will help you a lot in answering the questions.

Also, learn the difference between physical and chemical changes. The Science Class 8 Chapter 8 Nature of Matter: Elements, Compounds, and Mixtures solutions PDF will help you revise the concepts anytime.

4. Practice equations

Practice writing the simple equations like

Magnesium + Oxygen → Magnesium oxide

This will help you answer the reaction-based questions easily. Also, solve all the questions given in the NCERT solution for class 8 science chapter 8 Nature of Matter: Elements, Compounds, and Mixtures to score well in exams.

5. Understand the activities

The activities discussed in the chapter are so important and are often asked in exams. Do practice them attentively.

Also, focus on assertion and reason-type questions, as they are crucial to understanding. Also, practice the chapter 8 questions and answers as well.

NCERT Solutions for Class 8 Science Chapter 8: Topics

All the topics and subtopics covered in the Class 8 NCERT textbook are listed below. You can use the NCERT solutions for Class 8 Science Chapter 8 Nature of Matter: Elements, Compounds, and Mixtures ​​​​​ to understand these topics.

8.1 What Are Mixtures?

8.1.1 Is air a mixture?

8.1.2 Types of mixtures

8.2 What Are Pure Substances?

8.3 What Are the Types of Pure Substances?

8.3.1 Elements

8.3.2 Compounds

8.4 How Do We Use Elements, Compounds, and Mixtures?

8.5 What Are Minerals?

NCERT Chapter-Wise Solutions For Class 8 Science

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NCERT Solutions For Class 8 Subject-Wise

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NCERT Books and NCERT Syllabus

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