Matter in Our Surroundings – Very Short Answer Type Questions

CBSE Class 9 Chemistry — Matter in Our Surroundings | 50 Very Short Q&A

CBSE Board Exam — Systematic Use

1. Read definitions (5 min)

2. Practice VSAQs (15–20 min)

3. Attempt SA/LA after VSAQs

Use these VSAQs for quick daily practice. Each answer is short and precise to match exam expectations.

Intro — Basic Concepts (Questions 1–5)

1. What is matter?
Anything that occupies space and has mass.
2. Give two examples of matter.
Water and wood (both occupy space and have mass).
3. Does light occupy space? Is it matter?
Light does not occupy space and is not considered matter.
4. State the two basic properties of matter.
Occupies space (volume) and has mass.
5. Name the three common states of matter.
Solid, liquid and gas.

States of Matter — Characteristics (Questions 6–13)

6. What is a solid?
A state with definite shape and definite volume; particles closely packed in fixed positions.
7. What is a liquid?
A state with definite volume but no definite shape; takes the shape of its container.
8. What is a gas?
A state with no definite shape or volume; expands to fill the container.
9. Why do solids have fixed shape?
Because interparticle forces are strong and particles are in fixed positions.
10. Why are gases highly compressible?
Because their particles are far apart with large empty spaces between them.
11. Give one example each of solid, liquid and gas.
Solid: iron; Liquid: water; Gas: oxygen.
12. Which state of matter flows and why?
Liquids flow because particles can move/slide past each other.
13. Which state has maximum interparticle distance?
Gases have the maximum average distance between particles.

Change of State — Processes (Questions 14–21)

14. What is melting?
Change of solid to liquid on heating at the melting point.
15. What is freezing?
Change of liquid to solid on cooling (freezing point).
16. Define evaporation.
Liquid to gas at the surface occurring at any temperature below the boiling point.
17. Define boiling.
Liquid to gas throughout the liquid when vapour pressure equals external pressure (occurs at boiling point).
18. What is condensation?
Change of gas to liquid on cooling or pressure increase.
19. What is sublimation?
Direct change of solid to gas or gas to solid without passing through liquid (e.g., dry ice).
20. Give an example of sublimation.
Camphor or dry ice (solid CO₂) sublimate.
21. Why does evaporation cause cooling?
Because higher-energy molecules escape from the surface, lowering the average energy (temperature) of the remaining liquid.

Particle Nature of Matter (Questions 22–27)

22. State one idea of the particle theory of matter.
Matter is made of tiny particles (atoms/molecules) which are in constant motion.
23. How does temperature relate to particle motion?
Temperature is a measure of average kinetic energy; higher temperature → faster particle motion.
24. How do interparticle forces vary among states?
Strongest in solids, weaker in liquids, weakest/negligible in gases.
25. Why do particles in liquid move more than in solid?
Because interparticle forces are weaker and particles have more freedom to move.
26. What happens to particles on heating a solid?
Particles vibrate faster, gain energy and may break free to become liquid (melting).
27. Does particle size change on changing state?
No — particle size (atoms/molecules) remains same; only arrangement and separation change.

Diffusion & Brownian Motion (Questions 28–32)

28. What is diffusion?
Spontaneous mixing of particles due to their random motion.
29. Give a daily-life example of diffusion.
Smell of perfume spreading in a room.
30. In which medium is diffusion fastest?
Diffusion is fastest in gases, slower in liquids and slowest in solids.
31. What is Brownian motion?
Random zig-zag motion of tiny particles suspended in a fluid, observed under a microscope.
32. What does Brownian motion prove?
It gives evidence for the existence and motion of molecules/particles in matter.

Evaporation vs Boiling (Questions 33–37)

33. Can evaporation occur at room temperature?
Yes — evaporation can occur at any temperature below the boiling point.
34. Is boiling a surface or bulk phenomenon?
Boiling is a bulk phenomenon — it occurs throughout the liquid.
35. Name two factors that increase evaporation rate.
Higher temperature and larger surface area (also lower humidity and wind/water movement).
36. Does boiling cause cooling?
No — boiling itself does not produce cooling; evaporation causes cooling.
37. Why do clothes dry faster on a windy day?
Because moving air removes water vapour, increasing evaporation rate.

Forces, Compressibility & Expansion (Questions 38–42)

38. What causes compressibility of gases?
Large spaces between particles allow them to be pushed closer under pressure.
39. Are liquids easily compressible?
No — liquids are only slightly compressible because particles are close together.
40. Why do matter expand on heating?
Heating increases particle motion and average separation, causing expansion.
41. Which expands most on heating: solid, liquid or gas?
Gases expand the most on heating (for the same temperature rise and conditions).
42. Give one practical use of thermal expansion.
Mercury/Alcohol thermometers and bimetallic strips in thermostats.

Physical vs Chemical Change (Questions 43–46)

43. What is a physical change?
A change where no new substance is formed (e.g., melting of ice).
44. What is a chemical change?
A change that produces one or more new substances with different properties (e.g., burning paper).
45. Is dissolving sugar in water physical or chemical?
Physical — sugar molecules disperse but no new substance is formed.
46. Give an example of an irreversible change.
Burning of wood — it produces ash and gases and cannot be easily reversed.

Quick Revision / Mixed (Questions 47–50)

47. What is meant by 'bulk phenomenon'?
A change occurring throughout the material (e.g., boiling is a bulk phenomenon).
48. Which phenomenon gives cooling effect during sweating?
Evaporation of sweat from the skin causes cooling.
49. How does humidity affect evaporation?
High humidity slows evaporation because air already contains water vapour.
50. State one use of Brownian motion in science.
Provides experimental evidence for molecular motion, supporting kinetic theory; used in particle studies.

How to use these VSAQs: Practice daily for speed and precision. Try answering in one or two short sentences. Convert some into flashcards for quick last-minute revision.

Prepared strictly as per NCERT syllabus — ideal for CBSE Class 9 board exams.

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