---
title: "NCERT Solutions Class 8 Science Nature of Matter: Elements, Compounds, and Mixtures"
url: https://www.swavid.com/science/class/8/chapter/nature-of-matter-elements-compounds-and-mixtures/ncert-solutions
dateModified: 2026-10-07T16:14:34+00:00
---

# NCERT Solutions Class 8 Science Nature of Matter: Elements, Compounds, and Mixtures

This chapter's questions cover fundamental concepts about matter, mixtures, pure substances, elements, and compounds, including their classification, properties, and reactions.

Free PDF (7 pages): https://www.swavid.com/api/seo/pdf/ncert/science/class-8/swavid-ncert-solutions-class-8-science-chapter-8-nature-of-matter-elements-compounds-and-mixtures-00059cc43d.pdf

## Probe and ponder

### Question 1

*3 marks · Short answer*

Which of the entities in the picture above consist of matter, and which of them do not?

**Solution**

1. Entities that have mass and take up space, such as the students, trees, staircase, school bag, ball, and stick, consist of matter.
2. Entities like light, heat, electricity, thoughts, and emotions do not have mass or occupy space, so they do not consist of matter.
3. Everything in the picture that forms physical objects is matter, whereas non-physical aspects are not matter.

**Answer:** Physical objects like students, trees, and balls consist of matter, while light, heat, and emotions do not.

> Common mistake: Confusing forms of energy or feelings like light and emotions with matter.

### Question 2

*3 marks · Short answer*

How can elements be combined to form a compound?

**Solution**

1. Elements combine chemically in fixed ratios to form compounds.
2. During this combination, the constituent elements react to form something entirely new with properties different from the combining elements.
3. For example, hydrogen and oxygen combine chemically in a fixed ratio to form water.

**Answer:** Elements combine chemically in fixed ratios to form compounds.

> Common mistake: Thinking that elements in a compound are just mixed physically instead of combining chemically.

### Question 3

*3 marks · Short answer*

How could the discovery of a compound that absorbs carbon dioxide from the air contribute to solving environmental challenges?

**Solution**

1. Carbon dioxide is a major greenhouse gas contributing to global warming and climate change.
2. A compound that specifically absorbs carbon dioxide from the air can help directly reduce the concentration of this greenhouse gas in the atmosphere.
3. This would help combat global warming, lower the air quality index, and address critical environmental challenges.

**Answer:** It can help reduce greenhouse gases in the atmosphere, thereby combating global warming and environmental challenges.

> Common mistake: Failing to connect carbon dioxide absorption with greenhouse effect and global warming.

### Question 4

*3 marks · Short answer*

Share your questions?

**Solution**

1. Students can frame questions related to the properties and behaviors of matter observed around them.
2. An example of a valid question is: How can we separate the components of a mixture that have the same physical state?
3. Another example is: Do all pure substances consist of only one type of atom or can they have different atoms?

**Answer:** Questions related to the classification, properties, and separation of matter can be framed based on daily observations.

> Common mistake: Asking vague questions not related to the chapter concepts.

## Keep the curiosity alive

### Question 1

*1 mark · MCQ*

Consider the following reaction where two substances, A and B, combine to form a product C: $A + B \rightarrow C$. 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?

- A, B, and C are all compounds and only C has a fixed composition.
- C is a compound, and A and B have a fixed composition.
- A and B are compounds, and C has a fixed composition.
- A and B are elements, C is a compound, and has a fixed composition.

**Solution**

1. Substances A and B cannot be broken down further by chemical reactions, which means they are elements.
2. When elements combine chemically in a fixed ratio, they form a compound C which has a fixed composition.

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

> Common mistake: Confusing elements with compounds.

### Question 2

*1 mark · Assertion and reason*

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

- Both Assertion and Reason are true and Reason is the correct explanation for Assertion.
- Both Assertion and Reason are true, but Reason is not the correct explanation for Assertion.
- Assertion is true, but Reason is false.
- Assertion is false, but Reason is true.

**Solution**

1. Air is a uniform mixture of various gases like nitrogen, oxygen, and carbon dioxide.
2. A mixture is formed by mixing two or more substances without any chemical change, which correctly explains why air is a mixture.

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

> Common mistake: Thinking air is a single compound.

### Question 3

*3 marks · Short answer*

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

**Solution**

1. Water is a compound formed by the chemical combination of hydrogen and oxygen in a fixed ratio.
2. Hydrogen is a combustible fuel and oxygen supports combustion, whereas water extinguishes fire.
3. The properties of a compound are entirely different from the properties of the elements from which it is formed.

**Answer:** Water supports this statement as its properties (extinguishing fire) differ completely from its constituent elements, hydrogen (fuel) and oxygen (supports combustion).

> Common mistake: Stating that compounds retain the properties of their constituent elements.

### Question 4

*1 mark · MCQ*

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

- Elements — water, nitrogen, iron, air.
- Uniform mixtures— minerals, seawater, bronze, air.
- Pure substances— carbon dioxide, iron, oxygen, sugar.
- Non-uniform mixtures — air, sand, brass, muddy water.

**Solution**

1. Carbon dioxide, iron, oxygen, and sugar are all pure substances consisting of the same type of particles.
2. Water and air in option (i) and (iv) are mixtures, and minerals in option (ii) are mixtures of various compounds.

**Answer:** (iii) Pure substances— carbon dioxide, iron, oxygen, sugar.

> Common mistake: Incorrectly classifying air or seawater as pure substances or elements.

### Question 5

*3 marks · Short answer*

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.

**Solution**

1. Iron and magnesium are elements, while oxygen is also an element.
2. Moist air is a mixture containing oxygen and water vapour.
3. Iron oxide and magnesium oxide are compounds formed by the chemical combination of metals with oxygen.

**Answer:** Iron, magnesium, and oxygen are elements; moist air is a mixture; iron oxide and magnesium oxide are compounds.

> Common mistake: Classifying moist air as a pure substance or compound.

### Question 6

*3 marks · Short answer*

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.

**Solution**

1. Elements include aluminium, gold, oxygen, nitrogen, sulfur, and hydrogen.
2. Compounds include carbon dioxide, magnesium oxide, rust, iron sulfide, glucose, water, and baking soda.
3. Mixtures include sand, seawater, muddy water, air, fruit juice, and sodium chloride solution.

**Answer:** Substances are correctly classified into elements (aluminium, gold, oxygen, nitrogen, sulfur, hydrogen), compounds (carbon dioxide, magnesium oxide, rust, iron sulfide, glucose, water, baking soda), and mixtures (sand, seawater, muddy water, air, fruit juice).

> Common mistake: Classifying compounds like water or carbon dioxide as mixtures.

### Question 7

*3 marks · Short answer*

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.

**Solution**

1. When a mixture of iron filings and sulfur powder is heated, a new substance called iron sulfide is formed.
2. It is different from the original mixture because it is a compound where iron and sulfur lose their individual properties, cannot be separated by a magnet, and have a uniform composition throughout.
3. Word equation: $\text{Iron} + \text{Sulfur} \xrightarrow{\text{Heat}} \text{Iron sulfide}$

**Answer:** Iron sulfide is formed, which differs from the original mixture in properties, magnetic response, and separability.

> Common mistake: Stating that iron and sulfur can still be separated by a magnet after heating.

### Question 8

*3 marks · Short answer*

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

**Solution**

1. No, a substance cannot be classified as both an element and a compound.
2. An element is the simplest pure substance made up of identical atoms that cannot be broken down into simpler substances.
3. A compound is a pure substance composed of two or more elements combined chemically in a fixed ratio, which means their definitions and basic nature are mutually exclusive.

**Answer:** No, because elements are the simplest basic building blocks, whereas compounds are formed by the chemical combination of two or more elements.

> Common mistake: Confusing pure substances with elements or assuming mixtures can be pure.

### Question 9

*3 marks · Short answer*

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

**Solution**

1. If water were a mixture instead of a compound, its components (hydrogen and oxygen) would retain their individual properties.
2. Hydrogen is an extremely flammable fuel and oxygen supports combustion, so a mixture of them would be highly explosive and dangerous.
3. Water would not be able to extinguish fires or act as the stable liquid essential for life as we know it.

**Answer:** Water would be highly flammable and explosive instead of extinguishing fires, as its constituent gases would retain their individual properties.

> Common mistake: Forgetting that components of a mixture retain their individual properties.

### Question 10

*3 marks · Short answer*

Analyse Fig. 8.24. Identify Gas A. Also, write the word equation of the chemical reaction.

**Solution**

1. Gas A evolved in the test tube is hydrogen gas, which burns with a characteristic pop sound.
2. Iron reacts with dilute hydrochloric acid to form iron chloride and hydrogen gas.
3. Word equation: $\text{Iron} + \text{Dilute Hydrochloric acid} \rightarrow \text{Iron chloride} + \text{Hydrogen gas}$

**Answer:** Gas A is hydrogen gas. Word equation: Iron + Dilute Hydrochloric acid $\rightarrow$ Iron chloride + Hydrogen gas.

> Common mistake: Confusing hydrogen gas evolution with carbon dioxide or hydrogen sulfide.

### Question 11

*3 marks · Short answer*

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

**Solution**

1. Two examples of compounds made only from non-metals are carbon dioxide and water.
2. Carbon dioxide is used by plants during photosynthesis and in fire extinguishers.
3. Water is essential for drinking and domestic uses, and as a universal solvent in biological processes.

**Answer:** Carbon dioxide (used in photosynthesis and fire extinguishers) and water (used for drinking and in biological processes).

> Common mistake: Choosing compounds that contain metals like sodium chloride.

### Question 12

*3 marks · Short answer*

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

**Solution**

1. Gold is a natural, solid substance found in the Earth's crust with a definite elemental composition, which classifies it as a mineral.
2. Specifically, it is a native mineral because it exists as a pure element rather than a chemical compound.
3. At the same time, based on its physical and chemical properties such as malleability, ductility, and conductivity, it is classified as a metal.

**Answer:** Gold is a mineral because it occurs naturally as a solid native element in the Earth, and it is a metal due to its characteristic physical properties.

> Common mistake: Thinking all minerals must be compounds of multiple elements.

## Frequently asked questions

### How many questions are there in the NCERT Class 8 Science Chapter 8 exercises?

This chapter contains a total of 16 exercises, split between 4 questions in Probe and ponder and 12 questions in Keep the curiosity alive. SwaVid provides complete step-by-step solutions for all of them on this page.

### Which topics are covered in the exercises of this Class 8 Science chapter?

The questions cover important topics such as the classification of matter, distinction between elements and compounds, environmental applications of compounds, and elements, compounds, and mixtures in chemical reactions. You can find detailed explanations for these topics in SwaVid's free PDF available on this page.

### Which question types are considered the hardest in these exercises and how should I approach them?

Assertion-reason and short answer questions related to the classification of gold as a mineral and metal or compounds made from non-metals can be challenging. To approach them, carefully analyze the underlying scientific concepts rather than memorizing facts, and use SwaVid's solutions on this page to understand the correct reasoning.

### How can I write answers to get full marks in Class 8 Science examinations?

To secure full marks, write concise answers with proper scientific terminology, clear distinctions between elements and compounds, and relevant examples. SwaVid's expert-curated solutions on this page demonstrate the ideal structuring for every answer.

### Is the free PDF for this chapter available for download?

Yes, the complete chapter PDF along with detailed step-by-step solutions is available for free. You can easily access and download all the study material directly from this SwaVid page.

## Related pages

- [Class 8 Science chapters](https://www.swavid.com/science/class/8)

Solutions written by SwaVid, a personal AI tutor for Class 6 to 10 Maths and Science. Practise this chapter free: https://www.swavid.com/start/student