Question 1

Question 6Give two reasons to justify –(a) water at room temperature is a liquid.(b) an iron almirah is a solid at room temperature.

Accepted Answer

(a) Water at room temperature is a liquid because of the following reasons:At room temperature, water does not have a fixed shape and flows to fit the container's shape.A fixed volume is occupied by a fixed mass of water.(b) An iron almirah is a solid at room temperature because of the following reasons:It has a definite shape and volume at room temperature.It is rigid.

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BRIGHT TUTORIALS
  BRIGHT TUTORIALSCBSE Class IX | Academic Year 2026-20279403781999Excellence in Education
  Science | Chapter 1: Matter in Our SurroundingsWeb Content &mdash; Quick Reference
  
    Chapter 1: Matter in Our Surroundings &mdash; Quick Reference

states of matter
      particle nature
      change of state
      evaporation
      latent heat
      melting
      boiling
      sublimation

Quick Revision Points
      
        Matter has mass and occupies space; made of particles with spaces, motion, and attraction
Three states: Solid (fixed shape/volume), Liquid (fixed volume, not shape), Gas (neither fixed)
Melting point of ice = 0°C (273 K); Boiling point of water = 100°C (373 K)
Latent heat of fusion of ice = 334 J/g; Latent heat of vaporisation of water = 2260 J/g
Sublimation: solid → gas directly (camphor, dry ice, naphthalene)
Evaporation: surface phenomenon at all temperatures; causes cooling; factors: surface area, temperature, humidity, wind
Temperature conversion: T(K) = T(°C) + 273

Exam Tips for Chapter 1
      
        Read the detailed chapter notes for complete coverage of all NCERT topics.
        Practice all NCERT in-text and back exercise questions &mdash; they are frequently asked in exams.
        Focus on comparison tables, diagrams, and definitions &mdash; these are high-scoring areas.
        For numericals (if applicable), practice at least 20 problems of varying difficulty.
        Refer to the practice question bank (200+ questions) for thorough preparation.

Related Resources
      
        Detailed Notes: ch01-matter-in-our-surroundings.html
        Practice Questions: 100+ questions with answers in 05-practice-questions/
        Chapter Test: 30-mark test paper in 06-tests/chapter-tests-30marks/
        Formula Sheet: Complete formula reference in 03-teacher-aid/formula-sheet.html

BRIGHT TUTORIALSContact: 9403781999 | CBSE Class IX Coaching | 2026-2027

Question 2

Question 7Why is ice at 273 K more effective in cooling than water at the same temperature?

Accepted Answer

The latent heat of fusion of ice is 336 J g-1 so it absorbs 336 J of heat and changes to water at 0°C and then water at 0°C absorbs heat and temperature is raised. Therefore, ice at 0°C absorbs extra heat in comparison to water at 0°C (due to latent heat of fusion). Hence, ice at 0°C has greater cooling effect than water at 0°C.

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BRIGHT TUTORIALS
  BRIGHT TUTORIALSCBSE Class IX | Academic Year 2026-20279403781999Excellence in Education
  Science | Chapter 1: Matter in Our SurroundingsWeb Content &mdash; Quick Reference
  
    Chapter 1: Matter in Our Surroundings &mdash; Quick Reference

states of matter
      particle nature
      change of state
      evaporation
      latent heat
      melting
      boiling
      sublimation

Quick Revision Points
      
        Matter has mass and occupies space; made of particles with spaces, motion, and attraction
Three states: Solid (fixed shape/volume), Liquid (fixed volume, not shape), Gas (neither fixed)
Melting point of ice = 0°C (273 K); Boiling point of water = 100°C (373 K)
Latent heat of fusion of ice = 334 J/g; Latent heat of vaporisation of water = 2260 J/g
Sublimation: solid → gas directly (camphor, dry ice, naphthalene)
Evaporation: surface phenomenon at all temperatures; causes cooling; factors: surface area, temperature, humidity, wind
Temperature conversion: T(K) = T(°C) + 273

Exam Tips for Chapter 1
      
        Read the detailed chapter notes for complete coverage of all NCERT topics.
        Practice all NCERT in-text and back exercise questions &mdash; they are frequently asked in exams.
        Focus on comparison tables, diagrams, and definitions &mdash; these are high-scoring areas.
        For numericals (if applicable), practice at least 20 problems of varying difficulty.
        Refer to the practice question bank (200+ questions) for thorough preparation.

Related Resources
      
        Detailed Notes: ch01-matter-in-our-surroundings.html
        Practice Questions: 100+ questions with answers in 05-practice-questions/
        Chapter Test: 30-mark test paper in 06-tests/chapter-tests-30marks/
        Formula Sheet: Complete formula reference in 03-teacher-aid/formula-sheet.html

BRIGHT TUTORIALSContact: 9403781999 | CBSE Class IX Coaching | 2026-2027

Question 3

Question 8What produces more severe burns, boiling water or steam?

Accepted Answer

Steam has a higher heat content on account of high specific latent heat of condensation that is 2268 J g-1. Hence, steam at 100°C carries more heat than water. Therefore, burns caused by steam are more severe than burns caused by boiling water.

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BRIGHT TUTORIALS
  BRIGHT TUTORIALSCBSE Class IX | Academic Year 2026-20279403781999Excellence in Education
  Science | Chapter 1: Matter in Our SurroundingsWeb Content &mdash; Quick Reference
  
    Chapter 1: Matter in Our Surroundings &mdash; Quick Reference

states of matter
      particle nature
      change of state
      evaporation
      latent heat
      melting
      boiling
      sublimation

Quick Revision Points
      
        Matter has mass and occupies space; made of particles with spaces, motion, and attraction
Three states: Solid (fixed shape/volume), Liquid (fixed volume, not shape), Gas (neither fixed)
Melting point of ice = 0°C (273 K); Boiling point of water = 100°C (373 K)
Latent heat of fusion of ice = 334 J/g; Latent heat of vaporisation of water = 2260 J/g
Sublimation: solid → gas directly (camphor, dry ice, naphthalene)
Evaporation: surface phenomenon at all temperatures; causes cooling; factors: surface area, temperature, humidity, wind
Temperature conversion: T(K) = T(°C) + 273

Exam Tips for Chapter 1
      
        Read the detailed chapter notes for complete coverage of all NCERT topics.
        Practice all NCERT in-text and back exercise questions &mdash; they are frequently asked in exams.
        Focus on comparison tables, diagrams, and definitions &mdash; these are high-scoring areas.
        For numericals (if applicable), practice at least 20 problems of varying difficulty.
        Refer to the practice question bank (200+ questions) for thorough preparation.

Related Resources
      
        Detailed Notes: ch01-matter-in-our-surroundings.html
        Practice Questions: 100+ questions with answers in 05-practice-questions/
        Chapter Test: 30-mark test paper in 06-tests/chapter-tests-30marks/
        Formula Sheet: Complete formula reference in 03-teacher-aid/formula-sheet.html

BRIGHT TUTORIALSContact: 9403781999 | CBSE Class IX Coaching | 2026-2027

Question 4

Question 9Name A, B, C, D, E and F in the following diagram showing a change in its state.

Accepted Answer

(A) Solid to Liquid — Melting or liquefaction(B) Liquid to Gas — Evaporation or vaporization(C) Gas to liquid — Condensation(D) Liquid to Solid — Solidification(E) Solid to Gas — Sublimation(F) Gas to Solid — Deposition

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BRIGHT TUTORIALS
  BRIGHT TUTORIALSCBSE Class IX | Academic Year 2026-20279403781999Excellence in Education
  Science | Chapter 1: Matter in Our SurroundingsWeb Content &mdash; Quick Reference
  
    Chapter 1: Matter in Our Surroundings &mdash; Quick Reference

states of matter
      particle nature
      change of state
      evaporation
      latent heat
      melting
      boiling
      sublimation

Quick Revision Points
      
        Matter has mass and occupies space; made of particles with spaces, motion, and attraction
Three states: Solid (fixed shape/volume), Liquid (fixed volume, not shape), Gas (neither fixed)
Melting point of ice = 0°C (273 K); Boiling point of water = 100°C (373 K)
Latent heat of fusion of ice = 334 J/g; Latent heat of vaporisation of water = 2260 J/g
Sublimation: solid → gas directly (camphor, dry ice, naphthalene)
Evaporation: surface phenomenon at all temperatures; causes cooling; factors: surface area, temperature, humidity, wind
Temperature conversion: T(K) = T(°C) + 273

Exam Tips for Chapter 1
      
        Read the detailed chapter notes for complete coverage of all NCERT topics.
        Practice all NCERT in-text and back exercise questions &mdash; they are frequently asked in exams.
        Focus on comparison tables, diagrams, and definitions &mdash; these are high-scoring areas.
        For numericals (if applicable), practice at least 20 problems of varying difficulty.
        Refer to the practice question bank (200+ questions) for thorough preparation.

Related Resources
      
        Detailed Notes: ch01-matter-in-our-surroundings.html
        Practice Questions: 100+ questions with answers in 05-practice-questions/
        Chapter Test: 30-mark test paper in 06-tests/chapter-tests-30marks/
        Formula Sheet: Complete formula reference in 03-teacher-aid/formula-sheet.html

BRIGHT TUTORIALSContact: 9403781999 | CBSE Class IX Coaching | 2026-2027

Question 5

Question 2(a) Tabulate the differences in the characteristics of states of matter.(b) Comment upon the following:rigidity, compressibility, fluidity, filling a gas container, shape, kinetic energy and density.

Accepted Answer

(a) The difference in the characteristics of the three states of matter are:CharacteristicsSolidLiquidGasShapeFixed shapeNo Fixed shapeNo Fixed shapeVolumeFixed volumeFixed volumeNo Fixed volumeIntermolecular forceMaximumLess than solidsVery lessIntermolecular spaceVery lessMore than solidsMaximumCompressibilityNegligibleCompressibleHighly compressible(b) (i) Rigidity — It is the property of matter to continue to remain in its shape when treated with an external force.(ii) Compressibility — It is the property of the particles of matter to contract their intermolecular space when exposed to an external force, thereby increasing its density.(iii) Fluidity — It is the ability of a substance to flow or move about freely.(iv) Filling a gas container — The particles of gas fill the entire container as the intermolecular spaces between the gas molecules is very large and hence the particles are free to move about in all directions.(v) Shape — It is the definite structure of an object within an external boundary(vi) Kinetic energy — Motion allows particles to possess energy which is referred to as kinetic energy.K.E = 12\dfrac{1}{2}21​ mv2, where'm' is the mass and'v' is the velocity of the particle.(vii) Density — It is the mass of a unit volume of a substance.d = mv\dfrac{	ext{m}}{	ext{v}}vm​, whered is the density,m is the mass andv is the volume of the substance

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BRIGHT TUTORIALS
  BRIGHT TUTORIALSCBSE Class IX | Academic Year 2026-20279403781999Excellence in Education
  Science | Chapter 1: Matter in Our SurroundingsWeb Content &mdash; Quick Reference
  
    Chapter 1: Matter in Our Surroundings &mdash; Quick Reference

states of matter
      particle nature
      change of state
      evaporation
      latent heat
      melting
      boiling
      sublimation

Quick Revision Points
      
        Matter has mass and occupies space; made of particles with spaces, motion, and attraction
Three states: Solid (fixed shape/volume), Liquid (fixed volume, not shape), Gas (neither fixed)
Melting point of ice = 0°C (273 K); Boiling point of water = 100°C (373 K)
Latent heat of fusion of ice = 334 J/g; Latent heat of vaporisation of water = 2260 J/g
Sublimation: solid → gas directly (camphor, dry ice, naphthalene)
Evaporation: surface phenomenon at all temperatures; causes cooling; factors: surface area, temperature, humidity, wind
Temperature conversion: T(K) = T(°C) + 273

Exam Tips for Chapter 1
      
        Read the detailed chapter notes for complete coverage of all NCERT topics.
        Practice all NCERT in-text and back exercise questions &mdash; they are frequently asked in exams.
        Focus on comparison tables, diagrams, and definitions &mdash; these are high-scoring areas.
        For numericals (if applicable), practice at least 20 problems of varying difficulty.
        Refer to the practice question bank (200+ questions) for thorough preparation.

Related Resources
      
        Detailed Notes: ch01-matter-in-our-surroundings.html
        Practice Questions: 100+ questions with answers in 05-practice-questions/
        Chapter Test: 30-mark test paper in 06-tests/chapter-tests-30marks/
        Formula Sheet: Complete formula reference in 03-teacher-aid/formula-sheet.html

BRIGHT TUTORIALSContact: 9403781999 | CBSE Class IX Coaching | 2026-2027

Question 6

Question 3Give reasons(a) A gas fills completely the vessel in which it is kept.(b) A gas exerts pressure on the walls of the container.(c) A wooden table should be called a solid.(d) We can easily move our hand in the air, but to do the same through a solid block of wood, we need a karate expert.

Accepted Answer

(a) Gas is a state of matter in which intermolecular attraction is very weak and intermolecular space is so large that the particles become completely free to move randomly in the entire available space. Hence, it fills completely the vessel in which it is kept.(b) Gas molecules have negligible intermolecular forces and possess high kinetic energy, enabling them to move rapidly in all directions. This random motion leads to collisions among particles and with the container walls, resulting in the exertion of pressure by gas particles on the container.(c) A solid is characterized by a fixed shape and volume, and a wooden table also has these properties with its definite shape and volume, minimal intermolecular spaces, and rigidity. Therefore, it is appropriately called as a solid.(d) Air particles have very weak intermolecular force of attraction and hence very large intermolecular spaces. As a result, we can move our hands freely in the air. The particles in a solid block, on the other hand, are bound together by a strong force of attraction. As a result, there is no space between them. Hence, we will require a karate expert.

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BRIGHT TUTORIALS
  BRIGHT TUTORIALSCBSE Class IX | Academic Year 2026-20279403781999Excellence in Education
  Science | Chapter 1: Matter in Our SurroundingsWeb Content &mdash; Quick Reference
  
    Chapter 1: Matter in Our Surroundings &mdash; Quick Reference

states of matter
      particle nature
      change of state
      evaporation
      latent heat
      melting
      boiling
      sublimation

Quick Revision Points
      
        Matter has mass and occupies space; made of particles with spaces, motion, and attraction
Three states: Solid (fixed shape/volume), Liquid (fixed volume, not shape), Gas (neither fixed)
Melting point of ice = 0°C (273 K); Boiling point of water = 100°C (373 K)
Latent heat of fusion of ice = 334 J/g; Latent heat of vaporisation of water = 2260 J/g
Sublimation: solid → gas directly (camphor, dry ice, naphthalene)
Evaporation: surface phenomenon at all temperatures; causes cooling; factors: surface area, temperature, humidity, wind
Temperature conversion: T(K) = T(°C) + 273

Exam Tips for Chapter 1
      
        Read the detailed chapter notes for complete coverage of all NCERT topics.
        Practice all NCERT in-text and back exercise questions &mdash; they are frequently asked in exams.
        Focus on comparison tables, diagrams, and definitions &mdash; these are high-scoring areas.
        For numericals (if applicable), practice at least 20 problems of varying difficulty.
        Refer to the practice question bank (200+ questions) for thorough preparation.

Related Resources
      
        Detailed Notes: ch01-matter-in-our-surroundings.html
        Practice Questions: 100+ questions with answers in 05-practice-questions/
        Chapter Test: 30-mark test paper in 06-tests/chapter-tests-30marks/
        Formula Sheet: Complete formula reference in 03-teacher-aid/formula-sheet.html

BRIGHT TUTORIALSContact: 9403781999 | CBSE Class IX Coaching | 2026-2027

Question 7

Question 1Why does a desert cooler cool better on a hot dry day?

Accepted Answer

A dessert cooler works on the principle of evaporation. In hot and dry conditions, the air has low humidity, which means it can absorb more water vapour leading to more efficient evaporation and, consequently, better cooling effects compared to a humid day.

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BRIGHT TUTORIALS
  BRIGHT TUTORIALSCBSE Class IX | Academic Year 2026-20279403781999Excellence in Education
  Science | Chapter 1: Matter in Our SurroundingsWeb Content &mdash; Quick Reference
  
    Chapter 1: Matter in Our Surroundings &mdash; Quick Reference

states of matter
      particle nature
      change of state
      evaporation
      latent heat
      melting
      boiling
      sublimation

Quick Revision Points
      
        Matter has mass and occupies space; made of particles with spaces, motion, and attraction
Three states: Solid (fixed shape/volume), Liquid (fixed volume, not shape), Gas (neither fixed)
Melting point of ice = 0°C (273 K); Boiling point of water = 100°C (373 K)
Latent heat of fusion of ice = 334 J/g; Latent heat of vaporisation of water = 2260 J/g
Sublimation: solid → gas directly (camphor, dry ice, naphthalene)
Evaporation: surface phenomenon at all temperatures; causes cooling; factors: surface area, temperature, humidity, wind
Temperature conversion: T(K) = T(°C) + 273

Exam Tips for Chapter 1
      
        Read the detailed chapter notes for complete coverage of all NCERT topics.
        Practice all NCERT in-text and back exercise questions &mdash; they are frequently asked in exams.
        Focus on comparison tables, diagrams, and definitions &mdash; these are high-scoring areas.
        For numericals (if applicable), practice at least 20 problems of varying difficulty.
        Refer to the practice question bank (200+ questions) for thorough preparation.

Related Resources
      
        Detailed Notes: ch01-matter-in-our-surroundings.html
        Practice Questions: 100+ questions with answers in 05-practice-questions/
        Chapter Test: 30-mark test paper in 06-tests/chapter-tests-30marks/
        Formula Sheet: Complete formula reference in 03-teacher-aid/formula-sheet.html

BRIGHT TUTORIALSContact: 9403781999 | CBSE Class IX Coaching | 2026-2027

Question 8

Question 4Why are we able to sip hot tea or milk faster from a saucer rather than a cup?

Accepted Answer

Evaporation is a surface phenomenon. If the surface area is increased, the rate of evaporation increases. The surface area of a saucer is more than a cup, hence rate of evaporation is greater in a saucer than in a cup. As evaporation causes cooling, so hot tea or milk gets cooled quickly in a saucer than in a cup enabling us to sip it faster.

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BRIGHT TUTORIALS
  BRIGHT TUTORIALSCBSE Class IX | Academic Year 2026-20279403781999Excellence in Education
  Science | Chapter 1: Matter in Our SurroundingsWeb Content &mdash; Quick Reference
  
    Chapter 1: Matter in Our Surroundings &mdash; Quick Reference

states of matter
      particle nature
      change of state
      evaporation
      latent heat
      melting
      boiling
      sublimation

Quick Revision Points
      
        Matter has mass and occupies space; made of particles with spaces, motion, and attraction
Three states: Solid (fixed shape/volume), Liquid (fixed volume, not shape), Gas (neither fixed)
Melting point of ice = 0°C (273 K); Boiling point of water = 100°C (373 K)
Latent heat of fusion of ice = 334 J/g; Latent heat of vaporisation of water = 2260 J/g
Sublimation: solid → gas directly (camphor, dry ice, naphthalene)
Evaporation: surface phenomenon at all temperatures; causes cooling; factors: surface area, temperature, humidity, wind
Temperature conversion: T(K) = T(°C) + 273

Exam Tips for Chapter 1
      
        Read the detailed chapter notes for complete coverage of all NCERT topics.
        Practice all NCERT in-text and back exercise questions &mdash; they are frequently asked in exams.
        Focus on comparison tables, diagrams, and definitions &mdash; these are high-scoring areas.
        For numericals (if applicable), practice at least 20 problems of varying difficulty.
        Refer to the practice question bank (200+ questions) for thorough preparation.

Related Resources
      
        Detailed Notes: ch01-matter-in-our-surroundings.html
        Practice Questions: 100+ questions with answers in 05-practice-questions/
        Chapter Test: 30-mark test paper in 06-tests/chapter-tests-30marks/
        Formula Sheet: Complete formula reference in 03-teacher-aid/formula-sheet.html

BRIGHT TUTORIALSContact: 9403781999 | CBSE Class IX Coaching | 2026-2027

Question 9

Question 5What type of clothes should we wear in summer?

Accepted Answer

During summer we perspire more. During evaporation of sweat the particles at the surface gain energy from the surroundings or body surface and change into vapour. The heat energy equal to the latent heat of vaporization is absorbed leaving the body cool. Cotton being a good absorber of water helps in absorbing the sweat and exposing it to the atmosphere for easy evaporation. Hence, one should wear cotton clothes in summer.

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BRIGHT TUTORIALS
  BRIGHT TUTORIALSCBSE Class IX | Academic Year 2026-20279403781999Excellence in Education
  Science | Chapter 1: Matter in Our SurroundingsWeb Content &mdash; Quick Reference
  
    Chapter 1: Matter in Our Surroundings &mdash; Quick Reference

states of matter
      particle nature
      change of state
      evaporation
      latent heat
      melting
      boiling
      sublimation

Quick Revision Points
      
        Matter has mass and occupies space; made of particles with spaces, motion, and attraction
Three states: Solid (fixed shape/volume), Liquid (fixed volume, not shape), Gas (neither fixed)
Melting point of ice = 0°C (273 K); Boiling point of water = 100°C (373 K)
Latent heat of fusion of ice = 334 J/g; Latent heat of vaporisation of water = 2260 J/g
Sublimation: solid → gas directly (camphor, dry ice, naphthalene)
Evaporation: surface phenomenon at all temperatures; causes cooling; factors: surface area, temperature, humidity, wind
Temperature conversion: T(K) = T(°C) + 273

Exam Tips for Chapter 1
      
        Read the detailed chapter notes for complete coverage of all NCERT topics.
        Practice all NCERT in-text and back exercise questions &mdash; they are frequently asked in exams.
        Focus on comparison tables, diagrams, and definitions &mdash; these are high-scoring areas.
        For numericals (if applicable), practice at least 20 problems of varying difficulty.
        Refer to the practice question bank (200+ questions) for thorough preparation.

Related Resources
      
        Detailed Notes: ch01-matter-in-our-surroundings.html
        Practice Questions: 100+ questions with answers in 05-practice-questions/
        Chapter Test: 30-mark test paper in 06-tests/chapter-tests-30marks/
        Formula Sheet: Complete formula reference in 03-teacher-aid/formula-sheet.html

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Matter in Our Surroundings

Exercises

Intext Questions 2

Intext Questions 4