Important Questions Class 8 Science Chapter 8: Nature of Matter Elements Compounds and Mixtures

Matter is anything that has mass and occupies space.
Substances around us may exist as elements, compounds or mixtures depending on their composition.

Matter around us includes air, water, food, clothes, rocks, minerals, metals, fuels and building materials. Important Questions Class 8 Science Chapter 8 help students practise mixtures, uniform and non-uniform mixtures, pure substances, elements, compounds, alloys, air as a mixture, water as a compound, iron sulfide formation, minerals, graphene aerogel and classification of substances. The CBSE 2026 chapter explains these ideas through poha, sprout salad, lime water, dust in air, electrolysis of water, sugar heating, iron and sulfur reaction, alloys and minerals.

Key Takeaways

• Mixture: A mixture contains two or more substances that retain their individual properties.
• Pure Substance: A pure substance contains only one type of particle.
• Element: An element cannot be broken down into simpler substances by chemical reactions.
• Compound: A compound contains two or more elements chemically combined in a fixed ratio.

Important Questions Class 8 Science Chapter 8 Structure 2026

Important Questions Class 8 Science Chapter 8 with Answers

Nature of Matter: Elements, Compounds, and Mixtures explains how substances are classified by composition.
Students should identify whether a substance is a mixture, element or compound before explaining properties.
These nature of matter class 8 questions follow the NCERT 2026 chapter flow.

1. What does Important Questions Class 8 Science Chapter 8 mainly teach?

Important Questions Class 8 Science Chapter 8 mainly teach mixtures, pure substances, elements, compounds, alloys, minerals and classification of matter. The chapter explains how substances combine physically or chemically.

1. Mixture Skill: Identify components that retain properties.
2. Pure Substance Skill: Identify one type of particle.
3. Element Skill: Identify simplest substances.
4. Compound Skill: Identify fixed-ratio chemical combinations.
5. Final Result: Chapter 8 teaches classification of matter by composition.

2. What is the name of Class 8 Science Chapter 8?

The name of Class 8 Science Chapter 8 is Nature of Matter: Elements, Compounds, and Mixtures. It explains mixtures, pure substances and minerals.

1. Chapter Number: 8.
2. Chapter Name: Nature of Matter: Elements, Compounds, and Mixtures.
3. Textbook: Curiosity.
4. Final Result: Chapter 8 is about composition-based classification of matter.

3. Why does the chapter begin with everyday objects?

The chapter begins with everyday objects because almost everything around us is matter. Stairs, air, water, food, clothes, books and trees contain matter.

1. Matter Examples: Air, water and food.
2. Daily Objects: Clothes, shoes and books.
3. Common Feature: They have mass and occupy space.
4. Final Result: Everyday objects help introduce matter classification.

Class 8 Science Chapter 8 Important Questions

Class 8 Science Chapter 8 important questions focus on composition and separation.
The chapter shows that most objects around us contain two or more substances.
Students should distinguish scientific meaning from common usage.

4. What is matter?

Matter is anything that has mass and occupies space. Air, water, clothes, trees, food and books are examples.

1. Property 1: Has mass.
2. Property 2: Occupies space.
3. Examples: Air, water and iron.
4. Final Result: Matter includes substances and objects around us.

5. Are light, heat and electricity matter?

No, light, heat and electricity are not matter. They do not have mass and do not occupy space like substances.

1. Light: Not matter.
2. Heat: Not matter.
3. Electricity: Not matter.
4. Final Result: Matter must have mass and occupy space.

6. Why are most things around us not made of one substance?

Most things are not made of one substance because they contain two or more substances mixed or combined. Food, air, rocks and steel are examples.

1. Food: Contains many ingredients.
2. Air: Contains many gases.
3. Steel: Contains several elements.
4. Final Result: Many daily materials contain multiple substances.

7. What are the main categories of matter in this chapter?

The main categories are mixtures and pure substances. Pure substances are further classified into elements and compounds.

1. Category 1: Mixtures.
2. Category 2: Pure substances.
3. Pure Substance Types: Elements and compounds.
4. Final Result: Matter is classified as mixtures, elements and compounds.

Mixtures Class 8 Science Questions

Mixtures class 8 science questions explain substances formed by physical mixing.
The components of a mixture retain their properties.
They do not react chemically with each other.

8. What is a mixture?

A mixture is formed when two or more substances are mixed and each substance retains its properties. The substances do not react chemically.

1. Components: Two or more substances.
2. Property: Components retain properties.
3. Reaction: No chemical reaction occurs.
4. Final Result: A mixture is a physical combination of substances.

9. What are components of a mixture?

Components are the individual substances that make up a mixture. In sprout salad, green gram, chickpeas, onion and tomato are components.

1. Mixture: Sprout salad.
2. Component 1: Green gram.
3. Component 2: Chickpeas.
4. Component 3: Onion and tomato.
5. Final Result: Components are the parts of a mixture.

10. Why is poha a mixture?

Poha is a mixture because it contains several ingredients that retain their properties. These ingredients can be identified in the dish.

1. Ingredient: Flattened rice.
2. Ingredient: Spices and vegetables.
3. Property: Components remain identifiable.
4. Final Result: Poha is a mixture of food ingredients.

11. Why is sprout salad a mixture?

Sprout salad is a mixture because it contains visible components like sprouts, chickpeas, onion and tomato. These components retain their properties.

1. Visible Component: Sprouts.
2. Visible Component: Onion.
3. Visible Component: Tomato.
4. Final Result: Sprout salad is a non-uniform mixture.

12. Why is sugar dissolved in water a mixture?

Sugar dissolved in water is a mixture because sugar and water are physically mixed. Sugar retains sweetness and water remains the solvent.

1. Component 1: Sugar.
2. Component 2: Water.
3. Observation: Sweet solution forms.
4. Final Result: Sugar solution is a mixture.

13. Why do scientists separate mixtures?

Scientists separate mixtures to obtain pure substances. In daily life, separation often removes unwanted parts.

1. Science Aim: Obtain pure substances.
2. Daily Aim: Get useful component.
3. Example: Separate sand from water.
4. Final Result: Separation helps obtain required components.

Uniform and Non Uniform Mixtures Class 8

Uniform and non uniform mixtures class 8 questions explain visible and invisible component distribution.
Uniform mixtures have evenly distributed components.
Non-uniform mixtures show components separately.

14. What is a uniform mixture?

A uniform mixture has components evenly distributed throughout. Its components cannot be seen separately even with a microscope.

1. Distribution: Even throughout.
2. Appearance: Same in every part.
3. Example: Sugar solution.
4. Final Result: Uniform mixtures look the same throughout.

15. What is a non-uniform mixture?

A non-uniform mixture has components that are not evenly distributed. Its components are usually visible to the naked eye or magnifying device.

1. Distribution: Uneven.
2. Appearance: Different parts may look different.
3. Example: Sprout salad.
4. Final Result: Non-uniform mixtures show visible components.

16. Is air a uniform or non-uniform mixture?

Air is a uniform mixture of mainly nitrogen, oxygen, argon, carbon dioxide and water vapour. These gases are mixed evenly.

1. Main Gas: Nitrogen.
2. Second Major Gas: Oxygen.
3. Other Gases: Argon, carbon dioxide and water vapour.
4. Final Result: Air is a uniform mixture.

17. Is seawater a uniform mixture?

Seawater is a uniform mixture because dissolved salts are evenly distributed in water. Salt particles are not visible separately.

1. Component: Water.
2. Component: Dissolved salts.
3. Appearance: Uniform liquid.
4. Final Result: Seawater is a uniform mixture.

18. Is sand and water a uniform mixture?

Sand and water form a non-uniform mixture. Sand particles are visible and settle at the bottom.

1. Component: Sand.
2. Component: Water.
3. Observation: Sand settles separately.
4. Final Result: Sand and water form a non-uniform mixture.

19. Is oil and water a uniform mixture?

Oil and water form a non-uniform mixture because they remain as separate layers. They do not mix evenly.

1. Component 1: Oil.
2. Component 2: Water.
3. Observation: Layers form.
4. Final Result: Oil and water form a non-uniform mixture.

Air as a Mixture Class 8 Questions

Air as a mixture class 8 questions explain gases and pollutants present in air.
Air contains useful gases and may also contain dust or harmful pollutants.
The chapter confirms carbon dioxide through lime water.

20. Why is air called a mixture?

Air is called a mixture because it contains several gases physically mixed together. Nitrogen, oxygen, argon and carbon dioxide retain their properties.

1. Nitrogen: About 78%.
2. Oxygen: Supports life and combustion.
3. Carbon Dioxide: Present in small amount.
4. Final Result: Air contains physically mixed gases.

21. Why is oxygen important in air?

Oxygen is important because most living beings need it for survival. It also supports combustion.

1. Living Beings: Need oxygen.
2. Combustion: Oxygen helps burning.
3. Air: Contains oxygen.
4. Final Result: Oxygen supports life and combustion.

22. What is the role of nitrogen in air?

Nitrogen forms about 78% of air and does not take part in combustion. It is the major component of air.

1. Percentage: About 78%.
2. Combustion: Does not support burning.
3. Mixture Role: Major gas in air.
4. Final Result: Nitrogen is the largest component of air.

23. How does lime water show carbon dioxide in air?

Lime water turns milky when carbon dioxide reacts with calcium hydroxide. The white substance formed is calcium carbonate.

1. Lime Water: Calcium hydroxide solution.
2. Gas: Carbon dioxide from air.
3. Product: Calcium carbonate and water.
4. Final Result: Milky lime water proves carbon dioxide is present.

24. Write the word equation for carbon dioxide reacting with lime water.

The word equation is calcium hydroxide + carbon dioxide → calcium carbonate + water. Calcium carbonate makes lime water milky.

1. Reactants: Calcium hydroxide and carbon dioxide.
2. Product 1: Calcium carbonate.
3. Product 2: Water.
4. Final Result: Carbon dioxide turns lime water milky.

25. Are dust particles part of pure air?

No, dust particles are not an integral part of air. They are pollutants suspended in air.

1. Observation: Dust settles on black paper.
2. Nature: Suspended particles.
3. Category: Pollutants.
4. Final Result: Dust particles pollute air.

26. What are major air pollutants?

Major air pollutants include particulate matter, carbon monoxide, ozone, nitrogen dioxide and sulfur dioxide. Dust and soot are particulate matter.

1. Particulate Matter: Dust and soot.
2. Gas Pollutants: Carbon monoxide and sulfur dioxide.
3. Indicator: AQI describes air quality.
4. Final Result: Air pollutants include particles and gases.

Pure Substances Class 8 Questions

Pure substances class 8 questions explain scientific purity.
The scientific meaning of pure differs from the everyday meaning.
A pure substance has only one type of particle.

27. What is a pure substance in science?

A pure substance is matter that contains only one type of particle. It cannot be separated into other substances by physical processes.

1. Particle Type: Same throughout.
2. Physical Separation: Not possible into other substances.
3. Examples: Iron, oxygen and sugar.
4. Final Result: Pure substances contain identical particles.

28. How is scientific purity different from common purity?

In common usage, pure means unadulterated. In science, pure means the substance contains only one type of particle.

1. Common Meaning: Not adulterated.
2. Scientific Meaning: One type of particle.
3. Example: Milk may be unadulterated but still a mixture.
4. Final Result: Scientific purity depends on particle composition.

29. What is adulteration?

Adulteration is the illegal addition of cheaper or poor-quality substances to a product. It reduces quality and may harm health.

1. Purpose: Increase quantity or reduce cost.
2. Effect: Deteriorates quality.
3. Risk: Can be hazardous.
4. Final Result: Adulteration makes products unsafe or inferior.

30. Is milk a pure substance in science?

No, milk is not a pure substance in science. It contains water, fats, proteins, minerals and other substances.

1. Common Label: May say pure milk.
2. Scientific View: Contains many components.
3. Category: Mixture.
4. Final Result: Milk is a mixture in science.

31. Is sugar a pure substance?

Yes, sugar is a pure substance if it contains only sugar particles. It is also a compound made of carbon, hydrogen and oxygen.

1. Particle Type: Same sugar particles.
2. Category: Pure substance.
3. Compound Elements: Carbon, hydrogen and oxygen.
4. Final Result: Sugar is a pure compound.

32. Is soil a pure substance?

No, soil is not a pure substance. It contains minerals, organic matter, air, water and many particles.

1. Component: Minerals.
2. Component: Organic matter.
3. Component: Water and air.
4. Final Result: Soil is a mixture.

Elements Class 8 Science Questions

Elements class 8 science questions explain the simplest pure substances.
Elements cannot be broken into simpler substances by chemical reactions.
They are building blocks of all matter.

33. What is an element?

An element is a pure substance that cannot be broken down into simpler substances. It is made of identical atoms.

1. Particle: Atom.
2. Composition: One kind of atom.
3. Examples: Hydrogen, oxygen, iron and gold.
4. Final Result: Elements are simplest substances.

34. Why are elements called building blocks of matter?

Elements are called building blocks because compounds and many materials form from them. They cannot be chemically broken into simpler substances.

1. Simplest Substances: Elements.
2. Compounds: Form from elements.
3. Example: Water forms from hydrogen and oxygen.
4. Final Result: Elements build compounds and materials.

35. What are atoms?

Atoms are identical particles that make up an element. Atoms of one element differ from atoms of another element.

1. Iron: Made of iron atoms.
2. Gold: Made of gold atoms.
3. Oxygen: Made of oxygen atoms.
4. Final Result: Atoms are particles of elements.

36. What are molecules of elements?

Molecules of elements are stable particles formed when atoms of the same element combine. Hydrogen and oxygen form such molecules.

1. Hydrogen Molecule: Two hydrogen atoms.
2. Oxygen Molecule: Two oxygen atoms.
3. Element: Same kind of atoms.
4. Final Result: Element molecules contain atoms of one element.

37. How many elements are known at present?

At present, 118 elements are known. Most of them exist as solids at room temperature.

1. Known Elements: 118.
2. Most Common State: Solid.
3. Room Temperature: Many elements remain solid.
4. Final Result: There are 118 known elements.

38. Which elements are liquids at room temperature?

Mercury and bromine are liquid elements at room temperature. Mercury is a metal, and bromine is a non-metal.

1. Mercury: Liquid metal.
2. Bromine: Liquid non-metal.
3. Room Temperature: Both are liquids.
4. Final Result: Mercury and bromine are liquid elements.

39. What are metals and non-metals?

Metals and non-metals are categories of elements. Gold, silver, magnesium, iron and aluminium are metals, while carbon, sulfur, hydrogen and oxygen are non-metals.

1. Metals: Gold, iron and aluminium.
2. Non-metals: Carbon, sulfur and oxygen.
3. Intermediate Category: Metalloids like silicon and boron.
4. Final Result: Elements may be metals, non-metals or metalloids.

Compounds Class 8 Science Questions

Compounds class 8 science questions explain chemical combinations in fixed ratios.
The properties of a compound differ from those of its elements.
Compounds cannot be separated into elements by physical methods.

40. What is a compound?

A compound is a pure substance formed when two or more elements combine chemically in a fixed ratio. It has properties different from its elements.

1. Elements: Two or more.
2. Ratio: Fixed.
3. Properties: New and different.
4. Final Result: Compounds are fixed-ratio chemical combinations.

41. Why does a compound have different properties from its elements?

A compound has different properties because its elements combine chemically to form a new substance. The original element properties are not retained.

1. Hydrogen: Fuel.
2. Oxygen: Supports combustion.
3. Water: Extinguishes fire.
4. Final Result: A compound has new properties.

42. Why can compounds not be separated by physical methods?

Compounds cannot be separated by physical methods because their elements are chemically combined. Chemical methods are needed to break them.

1. Physical Method: Cannot separate elements.
2. Chemical Combination: Strong bonding.
3. Example: Water needs electricity to decompose.
4. Final Result: Compounds need chemical change for separation.

43. What is the difference between an element and a compound?

An element contains one kind of atom, while a compound contains two or more elements chemically combined. Both are pure substances.

1. Element: Iron or oxygen.
2. Compound: Water or sodium chloride.
3. Composition: One element versus fixed combination.
4. Final Result: Elements are simpler than compounds.

44. Can a substance be both an element and a compound?

No, a substance cannot be both an element and a compound. An element has one kind of atom, while a compound has different elements combined.

1. Element: One type of atom.
2. Compound: More than one element.
3. Same Substance: Cannot satisfy both definitions.
4. Final Result: Element and compound are different categories.

45. Is carbon dioxide a compound?

Yes, carbon dioxide is a compound. It contains carbon and oxygen chemically combined.

1. Element 1: Carbon.
2. Element 2: Oxygen.
3. Formula Idea: Fixed composition.
4. Final Result: Carbon dioxide is a compound of carbon and oxygen.

Water as a Compound Class 8 Questions

Water as a compound class 8 questions explain electrolysis and fixed composition.
Water forms from hydrogen and oxygen in a fixed ratio.
It does not behave like hydrogen or oxygen.

46. Why is water a compound?

Water is a compound because it contains hydrogen and oxygen chemically combined in a fixed ratio. Its properties differ from both elements.

1. Element 1: Hydrogen.
2. Element 2: Oxygen.
3. Atom Ratio: Hydrogen to oxygen is 2:1.
4. Final Result: Water is a compound of hydrogen and oxygen.

47. What happens when electric current passes through water?

Water breaks down into hydrogen and oxygen when electric current passes through it. This is a chemical change.

1. Substance: Water.
2. Process: Passing electricity.
3. Products: Hydrogen and oxygen.
4. Final Result: Electricity decomposes water into two gases.

48. How is hydrogen gas identified in water electrolysis?

Hydrogen gas is identified by bringing a burning candle near it. It burns with a pop sound.

1. Gas: Hydrogen.
2. Test: Burning candle near test tube.
3. Observation: Pop sound.
4. Final Result: Pop sound confirms hydrogen gas.

49. How is oxygen gas identified in water electrolysis?

Oxygen gas is identified when a candle flame glows brighter. Oxygen supports combustion.

1. Gas: Oxygen.
2. Test: Burning candle near test tube.
3. Observation: Flame glows brighter.
4. Final Result: Brighter flame confirms oxygen gas.

50. Why are gases formed during electrolysis not water vapour?

The gases are not water vapour because water vapour would condense back into water. The tests show hydrogen and oxygen instead.

1. Water Vapour: Would condense.
2. Hydrogen Test: Pop sound.
3. Oxygen Test: Flame glows brighter.
4. Final Result: Electrolysis produces hydrogen and oxygen.

51. Why would daily life change if water were only a mixture of hydrogen and oxygen?

Daily life would change because hydrogen and oxygen could be separated physically and would retain their properties. Water would not have its unique life-supporting properties.

1. Hydrogen: Fuel.
2. Oxygen: Supports combustion.
3. Water: Extinguishes fire and supports life.
4. Final Result: Water works differently because it is a compound.

Sugar as a Compound Class 8 Questions

Sugar as a compound class 8 questions explain decomposition by heating.
Sugar contains carbon, hydrogen and oxygen.
Heating sugar forms carbon and water.

52. Is sugar an element or compound?

Sugar is a compound. It contains carbon, hydrogen and oxygen chemically combined.

1. Element 1: Carbon.
2. Element 2: Hydrogen.
3. Element 3: Oxygen.
4. Final Result: Sugar is a compound of three elements.

53. What happens when sugar is heated?

Sugar first turns brown and then blackish. It decomposes to form carbon and water.

1. First Change: Brown colour.
2. Later Change: Blackish char.
3. Products: Carbon and water.
4. Final Result: Heating sugar decomposes it.

54. Why are water droplets seen when sugar is heated?

Water droplets appear because sugar decomposes and forms water. The droplets collect near the cooler open end of the boiling tube.

1. Sugar: Heated strongly.
2. Product: Water.
3. Observation: Droplets inside tube.
4. Final Result: Water forms from decomposed sugar.

55. What black substance is left after heating sugar?

Carbon is left behind after heating sugar. It appears as a blackish char.

1. Starting Substance: Sugar.
2. Heating: Causes decomposition.
3. Residue: Carbon.
4. Final Result: Black residue is carbon.

Iron and Sulfur Experiment Class 8 Questions

Iron and sulfur experiment class 8 questions compare mixture formation with compound formation.
Iron and sulfur form a mixture before heating.
On heating, they form iron sulfide, a new compound.

56. What is Sample A in the iron and sulfur experiment?

Sample A is a mixture of iron filings and sulfur powder. Its black and yellow particles can still be seen.

1. Component 1: Iron filings.
2. Component 2: Sulfur powder.
3. Nature: Mixture.
4. Final Result: Sample A is an iron-sulfur mixture.

57. What is Sample B in the iron and sulfur experiment?

Sample B is iron sulfide formed after heating iron and sulfur. It is a compound with new properties.

1. Reactants: Iron and sulfur.
2. Heating: Causes chemical reaction.
3. Product: Iron sulfide.
4. Final Result: Sample B is iron sulfide compound.

58. Why is Sample A attracted by a magnet?

Sample A is attracted by a magnet because it contains iron filings. Iron retains its magnetic property in the mixture.

1. Sample: Iron and sulfur mixture.
2. Magnetic Component: Iron.
3. Observation: Iron filings move towards magnet.
4. Final Result: Iron remains magnetic in Sample A.

59. Why is Sample B not attracted by a magnet?

Sample B is not attracted by a magnet because iron has chemically combined with sulfur to form iron sulfide. Iron no longer retains its original property.

1. Sample: Iron sulfide.
2. Property: New compound property.
3. Magnet Test: No attraction.
4. Final Result: Iron sulfide does not behave like iron filings.

60. How is Sample A different from Sample B?

Sample A is a mixture, while Sample B is a compound. Sample A components can be separated by a magnet, but Sample B cannot.

1. Sample A: Iron and sulfur mixture.
2. Sample B: Iron sulfide compound.
3. Separation: Sample A is physically separable.
4. Final Result: Sample B has new properties after heating.

61. What gas forms when Sample A reacts with dilute hydrochloric acid?

Hydrogen gas forms when iron in Sample A reacts with dilute hydrochloric acid. It is colourless and burns with a pop sound.

1. Reactant: Iron.
2. Acid: Dilute hydrochloric acid.
3. Gas: Hydrogen.
4. Final Result: Sample A produces hydrogen gas.

62. Write the word equation for iron reacting with dilute hydrochloric acid.

The word equation is iron + dilute hydrochloric acid → iron chloride + hydrogen gas. The hydrogen gas gives a pop sound.

1. Reactants: Iron and dilute hydrochloric acid.
2. Product 1: Iron chloride.
3. Product 2: Hydrogen gas.
4. Final Result: Iron produces hydrogen with dilute hydrochloric acid.

63. What gas forms when Sample B reacts with dilute hydrochloric acid?

Hydrogen sulfide gas forms when iron sulfide reacts with dilute hydrochloric acid. It has a rotten egg-like odour.

1. Reactant: Iron sulfide.
2. Acid: Dilute hydrochloric acid.
3. Gas: Hydrogen sulfide.
4. Final Result: Sample B produces hydrogen sulfide gas.

64. Write the word equation for iron sulfide reacting with dilute hydrochloric acid.

The word equation is iron sulfide + dilute hydrochloric acid → iron chloride + hydrogen sulfide. Hydrogen sulfide has a rotten egg-like odour.

1. Reactants: Iron sulfide and dilute hydrochloric acid.
2. Product 1: Iron chloride.
3. Product 2: Hydrogen sulfide.
4. Final Result: Iron sulfide produces hydrogen sulfide with acid.

Alloys Class 8 Questions

Alloys class 8 questions explain uniform mixtures of metals or metals with small amounts of non-metals.
Alloys often have properties different from their component metals.
Stainless steel, brass and bronze are examples.

65. What is an alloy?

An alloy is a uniform mixture of two or more metals or a metal with another element. Its components are mixed evenly.

1. Example 1: Stainless steel.
2. Example 2: Brass.
3. Example 3: Bronze.
4. Final Result: Alloys are uniform solid mixtures.

66. Why is stainless steel a mixture?

Stainless steel is a mixture because it contains iron, nickel, chromium and a small amount of carbon. These substances are mixed uniformly.

1. Main Component: Iron.
2. Other Metals: Nickel and chromium.
3. Non-metal: Small amount of carbon.
4. Final Result: Stainless steel is a uniform mixture.

67. What is brass made of?

Brass is made of copper and zinc. It is an alloy.

1. Metal 1: Copper.
2. Metal 2: Zinc.
3. Category: Alloy.
4. Final Result: Brass is a copper-zinc alloy.

68. What is bronze made of?

Bronze is made of copper and tin. In the chapter’s heritage note, Kamsya contains copper and tin.

1. Metal 1: Copper.
2. Metal 2: Tin.
3. Category: Alloy.
4. Final Result: Bronze is a copper-tin alloy.

69. What was Mishraloha?

Mishraloha was the name used for mixtures of two or more metals with properties distinct from their metals. Ancient Indian texts mention alloys.

1. Meaning: Mixture of metals.
2. Examples: Bronze and other alloys.
3. Use: Medicinal purposes in ancient texts.
4. Final Result: Mishraloha refers to metal mixtures or alloys.

Minerals Class 8 Science Questions

Minerals class 8 science questions explain naturally occurring solid substances found in rocks.
Most rocks are mixtures of minerals.
Minerals may be compounds or rarely pure elements.

70. What are minerals?

Minerals are natural solid substances found on Earth with fixed chemical composition. Most minerals are compounds.

1. Nature: Natural and solid.
2. Composition: Fixed chemical composition.
3. Examples: Quartz, calcite, mica, pyroxene and olivine.
4. Final Result: Minerals are natural solid substances.

71. Are all minerals compounds?

No, all minerals are not compounds. Some native minerals are pure elements such as gold, silver, copper, sulfur and carbon.

1. Most Minerals: Compounds.
2. Native Minerals: Pure elements.
3. Examples: Gold and sulfur.
4. Final Result: Minerals may be compounds or elements.

72. How is gold both a mineral and a metal?

Gold is a mineral because it occurs naturally as a solid substance on Earth. It is also a metal because it is an element with metallic properties.

1. Mineral: Naturally occurring.
2. Element: Gold atoms.
3. Metal: Shows metallic properties.
4. Final Result: Gold can be classified as both mineral and metal.

73. What minerals are used to make cement?

Cement is made using calcite, quartz, alumina and iron oxide. These are minerals or obtained from minerals.

1. Calcite: Used in cement.
2. Quartz: Used in cement.
3. Iron Oxide: Used in cement.
4. Final Result: Cement depends on mineral sources.

74. What is talcum powder made from?

Talcum powder is made from the mineral talc. Talc is a naturally occurring mineral.

1. Product: Talcum powder.
2. Mineral: Talc.
3. Source: Earth materials.
4. Final Result: Talcum powder comes from talc.

75. What is graphene aerogel?

Graphene aerogel is a very light material made from carbon. It is highly porous and can absorb substances.

1. Element: Carbon.
2. Property: Very light.
3. Use: Oil spill cleanup and energy-saving devices.
4. Final Result: Graphene aerogel is a lightweight carbon material.

NCERT Class 8 Science Chapter 8 Questions

NCERT Class 8 Science Chapter 8 questions test elements, compounds, mixtures, air, water, minerals and reactions.
Students should justify every classification with composition and separation method.
These NCERT Class 8 Science Chapter 8 questions follow the 2026 exercise pattern.

76. In A + B → C, A and B cannot be broken down into simpler substances. What are A, B and C?

A and B are elements, while C is a compound. C has a fixed composition because elements combine chemically.

1. A: Element.
2. B: Element.
3. C: Compound.
4. Correct Option: iv.
5. Final Result: Elements A and B form compound C.

77. Why is air a mixture?

Air is a mixture because two or more substances are mixed without chemical change. Its gases retain their properties.

1. Assertion: Air is a mixture.
2. Reason: Mixtures form without chemical change.
3. Conclusion: Reason explains assertion.
4. Final Result: Air is a mixture of gases.

78. Why does water have different properties from hydrogen and oxygen?

Water has different properties because hydrogen and oxygen chemically combine in a fixed ratio to form a compound. Water extinguishes fire.

1. Hydrogen: Fuel.
2. Oxygen: Supports combustion.
3. Water: Extinguishes fire.
4. Final Result: Compound properties differ from element properties.

79. Which set correctly lists pure substances: carbon dioxide, iron, oxygen and sugar?

The set is correct because all four are pure substances. Carbon dioxide and sugar are compounds, while iron and oxygen are elements.

1. Carbon Dioxide: Compound.
2. Iron: Element.
3. Oxygen: Element.
4. Sugar: Compound.
5. Final Result: All four are pure substances.

80. Why is “elements: water, nitrogen, iron, air” incorrect?

It is incorrect because water is a compound and air is a mixture. Only nitrogen and iron are elements.

1. Water: Compound.
2. Air: Mixture.
3. Nitrogen and Iron: Elements.
4. Final Result: The list mixes categories incorrectly.

81. Why is “uniform mixtures: minerals, seawater, bronze, air” incorrect?

It is incorrect because minerals are not always uniform mixtures. Seawater, bronze and air can be uniform mixtures.

1. Minerals: Often compounds or mixtures in rocks.
2. Seawater: Uniform mixture.
3. Bronze: Uniform alloy.
4. Air: Uniform gaseous mixture.
5. Final Result: Minerals do not fit the uniform mixture list.

82. Why is “non-uniform mixtures: air, sand, brass, muddy water” incorrect?

It is incorrect because air and brass are uniform mixtures. Muddy water is non-uniform, and sand may itself contain mixed particles.

1. Air: Uniform mixture.
2. Brass: Uniform alloy.
3. Muddy Water: Non-uniform mixture.
4. Final Result: The list contains uniform and non-uniform mixtures.

83. Classify iron, moist air and iron oxide.

Iron is an element, moist air is a mixture, and iron oxide is a compound. Iron oxide forms when iron reacts with moist air.

1. Iron: Element.
2. Moist Air: Mixture.
3. Iron Oxide: Compound.
4. Final Result: Rusting forms iron oxide compound.

84. Classify magnesium, oxygen and magnesium oxide.

Magnesium and oxygen are elements, while magnesium oxide is a compound. Magnesium oxide forms when magnesium burns in oxygen.

1. Magnesium: Element.
2. Oxygen: Element.
3. Magnesium Oxide: Compound.
4. Final Result: Burning magnesium forms a compound.

85. Classify carbon dioxide, aluminium, seawater and muddy water.

Carbon dioxide is a compound, aluminium is an element, seawater is a uniform mixture, and muddy water is a non-uniform mixture.

1. Carbon Dioxide: Compound.
2. Aluminium: Element.
3. Seawater: Mixture.
4. Muddy Water: Mixture.
5. Final Result: Each substance is classified by composition.

86. Classify gold, oxygen, air and sodium chloride.

Gold and oxygen are elements, air is a mixture, and sodium chloride is a compound. Sodium chloride contains sodium and chlorine.

1. Gold: Element.
2. Oxygen: Element.
3. Air: Mixture.
4. Sodium Chloride: Compound.
5. Final Result: Gold, oxygen, air and salt belong to different categories.

87. What new substance forms when iron and sulfur are heated?

Iron sulfide forms when iron filings and sulfur powder are heated. It differs from the original mixture in colour, texture and magnetic behaviour.

1. Reactants: Iron and sulfur.
2. Product: Iron sulfide.
3. Change: New compound forms.
4. Final Result: Heating iron and sulfur forms iron sulfide.

88. Write the word equation for iron and sulfur reaction.

The word equation is iron + sulfur → iron sulfide. This reaction forms a compound with new properties.

1. Reactant 1: Iron.
2. Reactant 2: Sulfur.
3. Product: Iron sulfide.
4. Final Result: Iron reacts with sulfur to form iron sulfide.

89. Identify Gas A when iron filings react with dilute hydrochloric acid.

Gas A is hydrogen gas. Iron reacts with dilute hydrochloric acid to produce iron chloride and hydrogen gas.

1. Reactants: Iron and dilute hydrochloric acid.
2. Product 1: Iron chloride.
3. Gas A: Hydrogen.
4. Final Result: Gas A is hydrogen.

90. Write the word equation for Fig. 8.24 reaction.

The word equation is iron + dilute hydrochloric acid → iron chloride + hydrogen gas. Hydrogen burns with a pop sound.

1. Metal: Iron.
2. Acid: Dilute hydrochloric acid.
3. Gas: Hydrogen.
4. Final Result: Iron and acid produce hydrogen gas.

Class 8 Science Chapter 8 Questions and Answers

Class 8 Science Chapter 8 questions and answers should use exact classification terms.
Students should not call every uniform material a pure substance.
These answers support quick revision for school tests.

91. Classify baking soda, glucose, sulfur and hydrogen.

Baking soda and glucose are compounds, while sulfur and hydrogen are elements. Each is a pure substance.

1. Baking Soda: Compound.
2. Glucose: Compound.
3. Sulfur: Element.
4. Hydrogen: Element.
5. Final Result: All four are pure substances.

92. Classify fruit juice, baking powder and rust.

Fruit juice and baking powder are mixtures, while rust is a compound. Baking powder contains baking soda and tartaric acid.

1. Fruit Juice: Mixture.
2. Baking Powder: Mixture.
3. Rust: Compound.
4. Final Result: Fruit juice and baking powder are mixtures.

93. Name two compounds made only from non-metals.

Carbon dioxide and water are compounds made only from non-metals. Carbon dioxide contains carbon and oxygen, while water contains hydrogen and oxygen.

1. Carbon Dioxide: Carbon and oxygen.
2. Water: Hydrogen and oxygen.
3. Category: Compounds.
4. Final Result: Both compounds contain only non-metals.

94. Give two uses of carbon dioxide.

Carbon dioxide is used in fire extinguishers and aerated drinks. Plants also use carbon dioxide in photosynthesis.

1. Use 1: Fire extinguishers.
2. Use 2: Soda water.
3. Biological Role: Photosynthesis.
4. Final Result: Carbon dioxide has safety, food and plant uses.

95. Give two uses of water.

Water is used for drinking and irrigation. It is also used for cleaning, cooking and many industrial processes.

1. Use 1: Drinking.
2. Use 2: Irrigation.
3. Use 3: Cleaning and cooking.
4. Final Result: Water is essential for life and daily work.

96. Why are elements, compounds and mixtures important in daily life?

They are important because daily materials are made from them. Air is a mixture, water is a compound, and iron is an element.

1. Air: Mixture of gases.
2. Water: Compound of hydrogen and oxygen.
3. Iron: Element used in construction.
4. Final Result: Daily life depends on elements, compounds and mixtures.

97. How do chemists use elements and compounds?

Chemists use elements and compounds to make medicines, vaccines and fertilisers. This supports health and food production.

1. Medicines: Use chemical compounds.
2. Vaccines: Help fight diseases.
3. Fertilisers: Improve crop production.
4. Final Result: Chemistry helps health and agriculture.

98. How do material scientists use mixtures?

Material scientists use mixtures to design strong and useful materials. Stainless steel is stronger and more durable than pure iron.

1. Material: Stainless steel.
2. Type: Alloy.
3. Property: Strong and durable.
4. Final Result: Mixtures can create improved materials.

99. How is Dhokra art connected with mixtures?

Dhokra art uses molten brass or bronze, which are alloys. These mixtures give strength and shiny golden colour to the figures.

1. Craft Regions: Bihar and Odisha.
2. Materials: Brass or bronze.
3. Process: Molten alloy fills a clay mould.
4. Final Result: Dhokra art uses metal alloys.

100. Why is discovering a carbon dioxide absorbing compound useful?

A carbon dioxide absorbing compound can help reduce carbon dioxide from air. This may support environmental cleanup and climate-related solutions.

1. Problem Gas: Carbon dioxide.
2. Possible Use: Air cleaning.
3. Environmental Link: Pollution control.
4. Final Result: Such compounds can help address environmental challenges.

Class 8 Science Chapter List