Class 9 Science - Chapter 1: Matter in Our Surroundings

Top 100 Important Exam Questions

1. Matter and Its Properties

• 1. What is matter? Give two examples. Copied!
• 2. What are the three states of matter? Copied!
• 3. Why is air considered a matter? Copied!
• 4. What is diffusion? Give an example. Copied!
• 5. Why do gases diffuse faster than liquids? Copied!
• 6. Why does a gas exert pressure? Copied!
• 7. What is compressibility? Which state of matter is highly compressible? Copied!
• 8. Why do solids have a definite shape and volume? Copied!
• 9. Why can liquids flow but solids cannot? Copied!
• 10. Why do gases not have a fixed volume? Copied!

2. Characteristics of Particles of Matter

• 11. What are the characteristics of particles of matter? Copied!
• 12. Why do particles of matter have space between them? Copied!
• 13. How does the rate of diffusion depend on temperature? Copied!
• 14. Why does a gas take the shape of its container? Copied!
• 15. What happens when sugar is added to water? Which property of matter does it show? Copied!
• 16. What happens to the particles of matter when heated? Copied!
• 17. Why does a wooden chair not take the shape of the container in which it is kept? Copied!
• 18. What is Brownian motion? Give an example. Copied!
• 19. How does an increase in temperature affect diffusion? Copied!
• 20. How do we know that particles of matter are constantly moving? Copied!

3. States of Matter and Their Interconversion

• 21. What is interconversion of states of matter? Copied!
• 22. Define sublimation with an example. Copied!
• 23. What is latent heat? Explain its types. Copied!
• 24. Define the boiling point of a liquid. Copied!
• 25. Define the melting point of a solid. Copied!
• 26. Why does the temperature remain constant during the melting of ice? Copied!
• 27. How does pressure affect the state of matter? Copied!
• 28. Explain why camphor disappears without leaving any residue. Copied!
• 29. How can we liquefy gases? Copied!
• 30. What is condensation? Give an example. Copied!

4. Effect of Temperature on States of Matter

• 31. How does heat affect the movement of particles? Copied!
• 32. Why does ice melt at 0°C? Copied!
• 33. Why does water boil at 100°C? Copied!
• 34. Why do clothes dry faster in summer than in winter? Copied!
• 35. Why do we feel cool when we put some acetone or petrol on our palm? Copied!
• 36. What is the role of latent heat in changing the state of matter? Copied!
• 37. Why does water remain cool in an earthen pot? Copied!
• 38. Why do we sweat more on humid days? Copied!
• 39. Why is ice at 0°C more effective in cooling than water at 0°C? Copied!
• 40. Why is steam at 100°C more dangerous than boiling water at 100°C? Copied!

5. Evaporation

• 41. Define evaporation. Copied!
• 42. What are the factors affecting evaporation? Copied!
• 43. Why does evaporation cause cooling? Copied!
• 44. Why do wet clothes dry faster on a windy day? Copied!
• 45. Why do we feel cool after taking a bath? Copied!
• 46. Why does the rate of evaporation increase with an increase in temperature? Copied!
• 47. How does the surface area affect the rate of evaporation? Copied!
• 48. Why do we feel cold when we apply deodorant or perfume? Copied!
• 49. Why does a desert cooler work better on a hot, dry day? Copied!
• 50. Why do farmers sprinkle water on crops during frost? Copied!

6. Differences Between States of Matter

• 51. Differentiate between solid, liquid, and gas based on shape and volume. Copied!
• 52. Differentiate between boiling and evaporation. Copied!
• 53. Differentiate between diffusion in gases and liquids. Copied!
• 54. Why do gases exert more pressure than solids and liquids? Copied!
• 55. Why do liquids have a fixed volume but no fixed shape? Copied!
• 56. Why is boiling considered a bulk phenomenon while evaporation is a surface phenomenon? Copied!
• 57. Why does the boiling point of water increase when salt is added to it? Copied!
• 58. What is the difference between melting and freezing? Copied!
• 59. How is pressure related to the liquefaction of gases? Copied!
• 60. What is the major difference between gas and vapor? Copied!

7. Practical Applications and Daily Life Examples

• 61. Why do naphthalene balls disappear over time? Copied!
• 62. Why does a steel container expand when heated? Copied!
• 63. How do gases help in inflating a balloon? Copied!
• 64. Why does ice float on water? Copied!
• 65. Why do gas cylinders have a warning sign about high pressure? Copied!
• 66. Why does warm air rise up? Copied!
• 67. Why do air bubbles expand as they rise in water? Copied!
• 68. Why do liquid droplets form spherical shapes? Copied!
• 69. Why does a pressure cooker reduce cooking time? Copied!
• 70. Why do mountaineers carry oxygen cylinders? Copied!

8. Numerical and Graph-Based Questions

• 71. A substance melts at 150°C. Is it solid or liquid at room temperature? Copied!
• 72. Draw a graph showing the change of state of ice to water and then to steam. Copied!
• 73. A gas is compressed from 10 L to 5 L. How does its pressure change? Copied!
• 74. If 1 kg of ice absorbs 334 kJ of heat energy, what is its latent heat of fusion? Copied!
• 75. A liquid at 80°C is left in a room at 30°C. What happens to its temperature over time? Copied!

9. Higher-Order Thinking Skills (HOTS) Questions

• 76. Why does ice at 0°C feel colder than water at 0°C? Copied!
• 77. Why is water used in car radiators? Copied!
• 78. Why does a balloon burst when too much air is blown into it? Copied!
• 79. Why is LPG stored in liquid form in cylinders? Copied!
• 80. How does an increase in humidity affect the rate of evaporation? Copied!

10. Miscellaneous Conceptual Questions

• 81. What is meant by kinetic energy of particles? Copied!
• 82. How does atmospheric pressure affect boiling point? Copied!
• 83. What is plasma? How is it different from gas? Copied!
• 84. What are Bose-Einstein Condensates? Copied!
• 85. Why do solids have high density compared to liquids and gases? Copied!
• 86. What is the effect of altitude on boiling point? Copied!
• 87. Why do gases not have a fixed shape? Copied!
• 88. Why does dry ice change into gas directly? Copied!
• 89. Why does alcohol evaporate faster than water? Copied!
• 90. Why is fog seen more in winter than in summer? Copied!
• 91. Why do pressure cookers cook food faster? Copied!
• 92. Why do icebergs float even though they are massive? Copied!
• 93. Why does salt help in melting ice? Copied!
• 94. How does a hot air balloon rise? Copied!
• 95. Why does sweating help cool the body? Copied!
• 96. Why do some liquids mix while others do not? Copied!
• 97. Why do helium balloons rise in the air? Copied!
• 98. Why does warm water dissolve substances faster than cold water? Copied!
• 99. Why do airplanes leave white trails in the sky? Copied!
• 100. How does the water cycle demonstrate changes in states of matter? Copied!