Looking for reliable SEBA Class 9 Science Chapter 1 (Matter in Our Surroundings) extra questions and answers for the 2026–27 academic year? Access essential additional practice questions, temperature unit conversion problems, short conceptual answers, latent heat explanations, and high-yield exam questions designed to help you score top marks in your annual exams.
Extra question and answer
1. What is matter?
Ans. Matter is anything that has mass and occupies space.
2. Give two examples of matter.
Ans. Air and water are two common examples of matter.
3. Does matter have mass?
Ans. Yes, all matter has mass.
4. Does matter occupy space?
Ans. Yes, all matter occupies space.
5. Name the five elements in Panch Tatva.
Ans. The five elements of Panch Tatva are Air, Earth, Fire, Water, and Sky.
6. State one modern way to classify matter.
Ans. One modern way to classify matter is based on its physical properties into solids, liquids, and gases.
7. What is a particle of matter?
Ans. A particle of matter is the extremely small, basic unit that makes up matter and is invisible to the naked eye.
8. Give one example showing that particles of matter move.
Ans. The spreading of perfume scent across a room demonstrates that particles of matter are constantly moving.
9. What is diffusion?
Ans. Diffusion is the process where particles of two different substances intermix on their own due to their continuous motion.
10. Do particles of matter attract each other?
Ans. Yes, particles of matter attract each other with varying degrees of force.
SEBA Class 9 Science Chapter 1 Extra Questions
11. Name the three states of matter.
Ans. The three basic states of matter are solid, liquid, and gas.
12. Give one property of solids.
Ans. Solids have a definite shape, distinct boundaries, and a fixed volume.
13. Give one property of liquids.
Ans. Liquids have a fixed volume but no definite shape, taking the shape of their container.
14. Give one property of gases.
Ans. Gases have no fixed shape or volume and are highly compressible.
15. What is melting?
Ans. Melting is the process in which a solid changes into a liquid upon heating.
16. What is boiling?
Ans. Boiling is the process in which a liquid changes into a gas state throughout its volume at its boiling point.
17. What is condensation?
Ans. Condensation is the process in which a gas changes into a liquid state upon cooling.
18. What is evaporation?
Ans. Evaporation is the process in which a liquid changes into vapor at any temperature below its boiling point.
19. Give one example of sublimation.
Ans. A common example of sublimation is camphor changing directly from a solid state to a gas state upon heating.
20. What is latent heat of fusion?
Ans. Latent heat of fusion is the amount of heat energy required to convert 1 kg of a solid into a liquid at its melting point at atmospheric pressure.o convert 1 kg of solid into liquid at its melting point.
Class 9 Science Chapter 1 Important Questions SEBA 2026-27
21. Explain why water droplets form on a cold glass.
Ans. Water vapor present in the surrounding air loses heat energy when it comes in contact with the cold surface of the glass, causing it to condense into visible liquid water droplets.
22. What are the characteristics of particles of matter?
Ans. Particles of matter have spaces between them, are in continuous motion, and exert forces of attraction on each other.
23. Why does sugar dissolve faster in hot water?
Ans. High temperature increases the kinetic energy and motion of water particles, which speeds up the rate of diffusion and causes sugar to dissolve much faster.
24. How does wind affect evaporation?
Ans. High wind speed carries away water vapor particles from the liquid surface, decreasing the surrounding moisture and increasing the overall rate of evaporation.
25. Why does sweating cool the body?
Ans. During evaporation, sweat absorbs heat energy from the body’s surface, which lowers the skin temperature and cools the body.
26. Explain the effect of temperature on the state of matter.
Ans. Increasing temperature increases the kinetic energy of particles, causing them to vibrate faster and overcome forces of attraction, which transforms a solid into a liquid and eventually into a gas.
27. Explain the effect of pressure on gases.
Ans. Increasing pressure brings gas particles significantly closer together, and applying cold temperatures alongside high pressure can compress and liquefy the gas.
28. What is deposition?
Ans. Deposition is the phase transformation process where a gas changes directly into a solid state without first passing through the liquid state.
29. Why does ice melt at a constant temperature?
Ans. Ice melts at a constant temperature because the supplied heat energy is used entirely as latent heat of fusion to break the attractive forces between ice particles rather than raising the overall temperature.
30. Explain why evaporation occurs even below boiling point.
Ans. Evaporation occurs below the boiling point because surface particles with higher kinetic energy overcome attractive forces and escape as vapor into the surrounding air.
Matter in Our Surroundings Class 9 SEBA Extra Question Answer
31. Why does perfume spread faster in warm air?
Ans. Warm air provides more kinetic energy to perfume particles, which causes them to move and diffuse much faster through the atmosphere.
32. Give one example showing diffusion in liquids.
Ans. Adding a crystal of potassium permanganate to a beaker of water demonstrates diffusion in liquids as the purple color gradually spreads evenly throughout the liquid.
33. Why is matter compressible in gases but not in solids?
Ans. Gases are compressible because their particles have large empty spaces between them that allow them to be pushed closer together, whereas solid particles are tightly packed with negligible space between them.
34. How does temperature affect the speed of diffusion?
Ans. Higher temperature increases the kinetic energy and speed of particles, which directly speeds up the rate of diffusion.
35. What is boiling point?
Ans. Boiling point is the specific temperature at which a liquid rapidly turns into a gas throughout its entire volume at atmospheric pressure.
36. What is latent heat of vaporization?
Ans. Latent heat of vaporization is the amount of heat energy required to convert 1 kg of a liquid into a gas state at its boiling point at atmospheric pressure.
37. Explain why solid CO₂ is called dry ice.
Ans. Solid carbon dioxide is called dry ice because it sublimates directly from a solid state to a gas state without turning into a liquid state when the pressure is reduced.
38. How does surface area affect evaporation?
Ans. Evaporation is a surface phenomenon, so increasing the surface area allows more particles to escape from the liquid surface at the same time, which speeds up the rate of evaporation.
39. Explain why sponge is compressible while sugar is not.
Ans. A sponge is compressible because it contains minute pores in which air is trapped, allowing the air to be expelled when pressed, whereas individual sugar crystals are rigid solids with no trapped air.
40. Why do aquatic animals survive in water?
Ans. Aquatic animals survive in water because atmospheric oxygen diffuses into water bodies, allowing these organisms to breathe dissolved oxygen using their specialized organs like gills.owing aquatic animals to breathe.
SEBA Class 9 Science Chapter 1 Practice Notes
41. Describe the Potassium Permanganate experiment.
Ans. When a few crystals of potassium permanganate are dissolved in a beaker of water, the deep purple color spreads evenly throughout the entire liquid. Even after diluting the solution multiple times, the water retains a light purple color, demonstrating that matter is composed of millions of tiny, continuously moving particles.
42. Explain the three states of matter with examples.
Ans. Matter exists in three distinct states:
- Solid State: Possesses a definite shape, fixed boundaries, and a definite volume, such as sugar.
- Liquid State: Has a fixed volume but no definite shape, taking the shape of its container, such as water.
- Gas State: Possesses neither a fixed shape nor a definite volume and is highly compressible, such as oxygen.
43. Explain why evaporation causes cooling.
Ans. During evaporation, the liquid particles present at the surface absorb heat energy from their surroundings to overcome forces of attraction and escape as vapor, which leaves the surrounding environment cooler.
44. Define melting, freezing, boiling, and condensation.
Ans.
- Melting: The process of a solid changing into a liquid state upon heating.
- Freezing: The process of a liquid changing into a solid state upon cooling.
- Boiling: The rapid transition of a liquid into a gas throughout its entire volume at its boiling point.
- Condensation: The phase change where a gas cools down and converts into a liquid state.
45. Describe sublimation and give examples.
Ans. Sublimation is the direct transformation of a substance from a solid state to a gas state upon heating, or vice versa, without passing through the intermediate liquid state. Common examples include camphor, naphthalene balls, and dry ice.
46. Explain latent heat with examples.
Ans. Latent heat is the hidden heat energy absorbed or released by a substance during a phase change without altering its overall temperature. For instance, the latent heat of fusion is absorbed when ice melts into water at 0°C, and the latent heat of vaporization is absorbed when water boils into steam at 100°C.
47. Compare particles in solids, liquids, and gases in terms of attraction, space, and movement.
Ans.
- Solids: Particles experience maximum inter-particle forces of attraction, have minimum inter-particle space, and show negligible particle movement.
- Liquids: Particles experience moderate forces of attraction, have larger inter-particle spaces, and move more freely than in solids.
- Gases: Particles experience negligible forces of attraction, possess the maximum inter-particle space, and move rapidly and randomly in all directions.
48. How does temperature and pressure change affect state of matter?
Ans. Increasing temperature increases kinetic energy, causing a solid to melt into a liquid and eventually boil into a gas. Increasing pressure alongside lowering temperature brings gas particles closer together to compress them into a liquid, while decreasing pressure allows solid carbon dioxide to change directly into a gas.
49. Explain the effect of heat on melting and boiling.
Ans. Supplying heat energy increases the kinetic energy of particles, causing them to vibrate more intensely and overcome inter-particle forces of attraction. This causes the solid structure to break down during melting and allows the liquid particles to break free completely into a gas state during boiling.
50. Why does ice float on water?
Ans. Ice floats on water because its rigid three-dimensional cage-like crystal structure leaves empty spaces between molecules, making its overall density lower than that of liquid water at the same temperature.
Class 9 Science Matter Important Questions
51. Give examples showing diffusion in solids, liquids, and gases.
Ans.
- Diffusion in Solids: Potassium permanganate crystals spreading their color throughout water.
- Diffusion in Liquids: A drop of ink or dissolved sugar spreading evenly through water.
- Diffusion in Gases: The fragrance of a lighted incense stick or perfume spreading rapidly across a room.
52. How does latent heat of fusion differ from latent heat of vaporization?
Ans. Latent heat of fusion is the heat required to convert 1 kg of a solid into a liquid at its melting point, whereas latent heat of vaporization is the heat required to convert 1 kg of a liquid into a gas at its boiling point. Latent heat of vaporization requires significantly more energy because complete separation of particles is needed to form a gas.
53. Why does ice at 0°C not melt instantly when heat is applied?
Ans. Ice at 0°C does not melt instantly because the initial heat energy supplied is used completely as latent heat of fusion to weaken and break the attractive forces binding the crystal lattice, keeping the temperature constant at 0°C until all the ice transforms into water.
54. Explain why evaporation is faster on a hot, windy, dry day.
Ans. On a hot, windy, and dry day, high temperature provides more kinetic energy to surface particles, strong winds carry away water vapor from the surface, and low humidity allows more liquid particles to escape rapidly into the dry air.
55. Explain why gas particles exert pressure on walls of container.
Ans. Gas particles move continuously, rapidly, and randomly in all directions, causing them to constantly collide with each other and strike the walls of the container, which exerts a continuous force per unit area on those walls.
56. Explain why CNG and LPG are stored under high pressure.
Ans. Compressed Natural Gas (CNG) and Liquefied Petroleum Gas (LPG) are stored under high pressure because applying pressure compresses large volumes of gas into compact cylinders, making them much easier to store and transport safely.
57. Why does sugar dissolve faster in hot water compared to cold water?
Ans. Sugar dissolves much faster in hot water because higher temperatures increase the kinetic energy and speed of water molecules, which allows them to collide more forcefully with sugar particles and speed up the diffusion process.
58. How do we measure pressure, density, mass, and volume of matter?
Ans. The standard SI units used to measure these physical quantities are:
- Pressure: Measured in Pascal (Pa).
- Density: Measured in kilograms per cubic meter (kg/m³).
- Mass: Measured in kilograms (kg).
- Volume: Measured in cubic meters (m³).
59. Explain freezing with example.
Ans. Freezing is the process in which a liquid loses heat energy, causing its particles to slow down until attractive forces pull them into fixed positions to form a solid, such as water turning into ice when cooled to 0°C.
60. Describe the process of condensation with example.
Ans. Condensation occurs when a gas loses heat energy, causing its particles to lose kinetic energy, slow down, and come closer together under attractive forces to form a liquid, such as water vapor forming droplets on the cold outer surface of a glass filled with ice water.
🔬 Updated Extra Questions Guide Notice: This page features an extensive collection of SEBA Class 9 Science Chapter 1 (Matter in Our Surroundings) Extra Questions and Detailed Answers updated for the 2026–27 academic session. All physical chemistry concepts, sublimation examples, evaporation factors, and temperature conversion calculations strictly follow the latest revised Assam Board (SEBA) curriculum.
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