studycbse.online

Class 8 Science Chapter 8 – Nature of Matter: Elements, Compounds, and Mixtures | NCERT Curiosity Worksheet

Practise Class 8 Science Chapter 8 – Nature of Matter: Elements, Compounds, and Mixtures with this easy NCERT Curiosity worksheet. Includes important questions and revision exercises to strengthen understanding of elements, compounds and mixtures and prepare effectively for class tests and exams.

Chapter 8 Worksheet

Nature of Matter: Elements, Compounds, and Mixtures
Curiosity – Textbook of Science for Grade 8
100%
Instructions:
  • Read each question carefully.
  • Write your answers in simple and clear language.
  • For classification questions, give suitable reasons wherever required.
  • Try the challenge questions after completing the basic questions.

Section A – Multiple Choice Questions

1 mark 1. Which of the following is a mixture?
  1. Oxygen
  2. Gold
  3. Air
  4. Water
1 mark 2. Which one of the following is an element?
  1. Carbon dioxide
  2. Iron
  3. Water
  4. Sodium chloride
1 mark 3. Which of the following is a compound?
  1. Oxygen
  2. Air
  3. Water
  4. Brass
1 mark 4. Which of the following is a non-uniform mixture?
  1. Sugar solution
  2. Air
  3. Oil and water
  4. Seawater
1 mark 5. Which gas is produced when iron reacts with dilute hydrochloric acid?
  1. Oxygen
  2. Hydrogen
  3. Nitrogen
  4. Carbon dioxide
1 mark 6. Which of the following is an alloy?
  1. Oxygen
  2. Brass
  3. Water
  4. Sulfur

Section B – Fill in the Blanks

7. The substances that make up a mixture are called its __________.
8. A pure substance can be either an __________ or a __________.
9. The two elements present in water are __________ and __________.
10. An alloy is a mixture of __________.
11. The gas present in the largest amount in air is __________.
12. Iron and sulfur react on heating to form __________.

Section C – True or False

13. A mixture is formed when substances are chemically combined in a fixed ratio.
14. Air is a uniform mixture.
15. Water is a compound.
16. Iron sulfide has the same properties as iron and sulfur.
17. The components of a mixture retain their individual properties.
18. Gold can occur naturally as a mineral.

Section D – Classify the Substances

19. Classify the following as element, compound, or mixture.
SubstanceClassification
Oxygen
Carbon dioxide
Air
Iron
Water
Brass
Sulfur
Sodium chloride
Seawater
Iron sulfide

Section E – Very Short Answer Questions

20. What is a mixture?
21. What are the components of a mixture?
22. Give one example of a uniform mixture.
23. Give one example of a non-uniform mixture.
24. What is a pure substance?
25. Name the two types of pure substances.
26. What is an element?
27. What is a compound?
28. Why is air considered a mixture?

Section F – Short Answer Questions

29. Write two differences between a mixture and a compound.
30. Why can the components of a mixture usually be separated by physical methods?
31. Why cannot the elements of a compound be separated by ordinary physical methods?
32. Why is water called a compound?
33. Why is brass considered a mixture?
34. What happens when iron filings and sulfur powder are heated together?

Section G – Give Reasons

35. Give a reason: Air is a mixture.
36. Give a reason: Water is a compound.
37. Give a reason: Iron sulfide is different from a mixture of iron and sulfur.
38. Give a reason: Stainless steel is a mixture.

Section H – Complete the Word Equations

39. Complete the following word equation:

Calcium hydroxide + Carbon dioxide → __________ + __________
40. Complete the following word equation:

Water → __________ + __________
41. Complete the following word equation:

Iron + Sulfur → __________
42. Complete the following word equation:

Iron + Dilute Hydrochloric acid → __________ + __________

Section I – Think and Answer

43. A student mixes sand and water in a beaker. Is the mixture uniform or non-uniform? Give a reason.
44. A student dissolves sugar completely in water. What type of mixture is formed? Why?
45. A mixture contains iron filings and sulfur powder. How can you separate the iron from the mixture?
46. A black substance is formed when iron and sulfur are heated together. It is not attracted by a magnet. What could the substance be?
47. Why can sugar dissolved in water be separated by evaporation, but the elements present in sugar cannot be separated by evaporation?
48. A student says, “Since air contains many gases, it must be a non-uniform mixture.” Is the statement correct? Explain.

Section J – Compare

49. Complete the following table.
FeatureMixtureCompound
How are substances combined?
Ratio of components
Properties of components
Can components be separated physically?

Section K – Application Based Questions

3 marks 50. Riya has three samples: air, water, and iron. Classify each as a mixture, compound, or element. Give one reason for each classification.
3 marks 51. A mixture contains iron filings, sand, and salt. Suggest a simple sequence of methods to separate all three components.
3 marks 52. A colourless liquid is tested. On passing electric current through it, two gases are produced. One gas burns with a pop sound and the other supports burning. What could the liquid be? Name the two gases.
3 marks 53. A sample looks completely uniform. Can you always conclude that it is a pure substance? Explain with an example.

Section L – Case Study

Read the situation and answer the questions.

Aman mixes iron filings and sulfur powder. Before heating, he observes that the iron filings can be attracted by a magnet. He then heats the mixture strongly. A black substance is formed. After cooling, the black substance is not attracted by a magnet.

54 (a). What type of substance was present before heating?
54 (b). What new substance is formed after heating?
54 (c). Is the substance formed a mixture or a compound?
54 (d). Write the word equation for the reaction.

Section M – Challenge Questions

55. A student says, “Every substance that contains more than one element is a mixture.” Do you agree? Explain with an example.
56. Water contains hydrogen and oxygen. Why does water not show all the properties of hydrogen and oxygen?
57. A sample contains only one type of particle. Can it be called a pure substance? Explain.
58. Why is gold considered both an element and a mineral when it occurs naturally in the Earth?
59. Explain why stainless steel is useful for making utensils even though pure iron has different properties.

Section N – Quick Revision

60. Write one example each of:
  1. An element
  2. A compound
  3. A uniform mixture
  4. A non-uniform mixture
  5. An alloy
  6. A mineral
Worksheet Complete — Revise the concepts and try the challenge questions again.

Class 8 Science Chapter 8 Worksheet, Class 8 Science Curiosity Chapter 8 Worksheet, Nature of Matter Elements Compounds and Mixtures Worksheet, Class 8 Curiosity Chapter 8 Worksheet, NCERT Class 8 Science Worksheet, Class 8 Science Practice Worksheet, Class 8 Science Questions and Answers, CBSE Class 8 Science Worksheet, Class 8 Science Revision Worksheet, Elements Compounds and Mixtures Questions, Class 8 Science Curiosity Worksheet, NCERT Class 8 Science Curiosity