1
Which of these is not matter?
💡 Hint:
Something with no mass and no volume.
Explanation:
Love is not matter. Air, almonds and a cold drink occupy space.
Class 9 · Science · Chapter 1 · बिहार बोर्ड (BSEB)CBSE · NCERT 2026-27
Matter in Our Surroundings
Matter in Our Surroundings
How to use this page:
1. Read — 1.1 salt · 1.2 dilution · 1.3 incense · 1.4 ink-honey · 1.5 hot-cold · 1.6–1.8 attraction · 1.9–1.11 states · 1.12 ice · 1.13 sublimation · 1.14 evaporation, diagram, worked example, board tip
2. Check — each lesson has its own questions; the number follows the lesson
3. Mastery ★ — all of that lesson correct. Redo the wrong ones
4. Use the solid, liquid and gas memory picture — particles stay packed and fixed in a solid, slide in a liquid, and stay far apart in a gas.
In the Bihar book this is chapter 1. The first chapter of the NCERT 2026-27 Exploration book is different. Progress stays in this browser.
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- 1 Particles and the space between them — Activities 1.1, 1.2
- 2 Particles keep moving — Activities 1.3, 1.4, 1.5
- 3 Particles attract one another — Activities 1.6, 1.7, 1.8
- 4 Solid, liquid and gas — Activities 1.9, 1.10, 1.11
- 5 Temperature, melting point and latent heat — Activity 1.12
- 6 Pressure and sublimation — Activity 1.13
- 7 Evaporation and cooling — Activity 1.14
- Chapter winner — every lesson at mastery ★
🎬 Shorts
This chapter has no Short on the channel yet, so ten empty cards are not shown. The notes, diagrams and checks are complete.
📄 PDF download — notes + answer key
Particles and the space between them — Activities 1.1, 1.2
कण और उनके बीच की जगह — क्रियाकलाप 1.1, 1.2 · Bihar book 1.1 · Activities 1.1, 1.2
Matter is anything that occupies space and has massNotes
Air, food, a stone, clouds, stars, plants, animals, a drop of water and a grain of sand are all matter. Ancient India sorted them into five elements: air, earth, fire, sky and water. In this chapter we look only at physical properties. Chemical nature comes in later chapters.
The SI unit of mass is the kilogram. The SI unit of volume is the cubic metre. 1 L = 1 dm³ = 1000 mL, and 1 mL = 1 cm³.
Matter is not one unbroken block like a plank of wood. It is made of small particles. There is space between the particles, and they are so small that even one crystal holds millions of them.
Activities 1.1 and 1.2 — salt, then potassium permanganateActivity
1.1. Take a 100 mL beaker. Fill it about half with water and mark the level. Dissolve salt or sugar with a glass rod. The level hardly rises. The salt from the spoon spreads through the water, because its particles fit into the spaces of the water particles. The same happens in tea, coffee and lemonade.
1.2. Dissolve 2 or 3 crystals of potassium permanganate in 100 mL of water. Take about 10 mL of this solution and put it into 90 mL of clear water. Then take 10 mL of that and put it into another 90 mL. Do this 5 to 8 times. The colour grows pale, but it remains. A few crystals can colour about 1000 L of water. The same activity can be done with 2 mL of Dettol. The smell remains even after repeated dilution.
Worked exampleExample
Question: A 100 mL beaker is half full of water. Why does the level not rise when a spoon of salt dissolves?
Answer: The salt does not vanish. Its particles spread into the empty spaces between the water particles. So the volume stays almost the same. That is the conclusion of Activity 1.1.
10-second revision
- Matter has both mass and volume
- 1.1: there is space between particles, the level does not rise
- 1.2: the colour remains even after 5 to 8 dilutions
Board tip · BSEBBoard tip
1.1 is about space and 1.2 is about size. Do not join the two in one sentence of the answer.
Board tip · CBSEBoard tip
Write the units: 1 L = 1000 mL = 1000 cm³. The cubic metre is the SI unit of volume.
Check your understandingall correct = mastery ★
2
The water level does not rise when salt dissolves because the salt is destroyed.
Explanation:
False — particles of salt move into the spaces between particles of water.
3
In Activity 1.2 the solution is diluted ______ to 8 times.
💡 Hint:
Each time, 10 mL into 90 mL.
Explanation:
5 to 8 times.
4
1 mL is equal to —
💡 Hint:
1 L = 1000 mL.
Explanation:
1 mL = 1 cm³. 1 L = 1 dm³ = 1000 mL.
5
Write one conclusion about particles from Activity 1.1 and one from Activity 1.2.
Model answer (board format)
Activity 1.1 shows that there is space between particles, so the level does not rise when salt dissolves. Activity 1.2 shows that particles are very small, because the colour remains after 5 to 8 dilutions.
Check your answer:
Particles keep moving — Activities 1.3, 1.4, 1.5
कण चलते रहते हैं — क्रियाकलाप 1.3, 1.4, 1.5 · Section 1.2.2 · diffusion · kinetic energy
Mixing on their own is diffusionNotes
Particles keep moving. The energy of this motion is called kinetic energy. Raise the temperature and the particles move faster, so the kinetic energy rises.
When particles of two substances enter each other’s spaces on their own, that is diffusion. Heating makes diffusion faster. That is why the smell of hot food reaches several metres, while you have to go close to smell cold food.
Activities 1.3, 1.4 and 1.5 — smell, ink, hot and cold waterActivity
1.3. Put an unlit incense stick in a corner of the class. Write how close you must go to smell it. Then light it. The smell reaches you even from a seat far away, because the warmer particles spread faster through the air.
1.4. Take two beakers of water. Slide one drop of blue or red ink slowly along the wall of the first. Put honey the same way into the second. Do not stir. The ink colour spreads soon. Honey spreads late. The ink may take hours or days to colour the water evenly.
1.5. Drop one crystal of copper sulphate or potassium permanganate into a glass of hot water and one into cold water. Do not stir. Let the crystal settle. Colour shows just above the crystal. With time the colour spreads. Mixing is faster in hot water. These three activities show that particles move and diffuse on their own, and the rate rises when the temperature rises.
Worked exampleExample
Question: Why does a drop of honey spread more slowly than ink, and why does the crystal colour spread faster in hot water?
Answer: Particles of honey are held more tightly, so diffusion is slow. In hot water the kinetic energy of the particles is higher, so the rate of mixing in Activity 1.5 rises.
10-second revision
- Diffusion is particles mixing on their own
- Raise the temperature and both kinetic energy and diffusion increase
- 1.3 gas, 1.4 liquid, 1.5 the effect of temperature
Board tip · BSEBBoard tip
The reason for hot food is diffusion and kinetic energy. Only “the air moves” is incomplete.
Board tip · CBSEBoard tip
In 1.4 ink is fast and honey is slow. In 1.5 hot water is fast. Do not swap the facts.
Check your understandingall correct = mastery ★
1
Particles of two substances mixing on their own is called —
💡 Hint:
The smell of the incense stick is this.
Explanation:
It is called diffusion.
2
The kinetic energy of particles falls when the temperature is raised.
Explanation:
False — on heating, particles move faster and the kinetic energy rises.
3
In Activity 1.5 the crystal spreads faster in ______ water.
💡 Hint:
Do not stir.
Explanation:
In hot water.
4
Ink spreads sooner than honey because —
💡 Hint:
Activity 1.4.
Explanation:
Ink particles diffuse more freely than honey.
5
Why do you smell cold food only from close by, but hot food from far away?
Model answer (board format)
Particles of hot food have more kinetic energy, so they diffuse quickly through the air. Particles of cold food are slower, so the smell does not travel far.
Check your answer:
6
In Activity 1.3, for the smell of an unlit incense stick —
💡 Hint:
After lighting, it arrives from far away.
Explanation:
You have to go close for an unlit stick. After lighting, the smell travels far.
Particles attract one another — Activities 1.6, 1.7, 1.8
कण एक-दूसरे को खींचते हैं — क्रियाकलाप 1.6, 1.7, 1.8 · Section 1.2.3 · force of attraction
The attraction is not the same in every substanceNotes
A force of attraction between particles holds them together. The strength of this force changes from one substance to another. It is strongest in a solid, in between in a liquid, and weakest in a gas.
A diver can cut through water because the attraction of water particles is not as strong as in a block of wood. A hand moves easily through air because the attraction in a gas is weaker still.
Activities 1.6, 1.7 and 1.8 — chains, a nail and a stream of waterActivity
1.6. Make four groups in the field. The first locks arms from the back like Idu-Mishmi dancers. The second holds hands in a chain. The third touches only with fingertips. The fourth group runs and tries to break the three chains. The fingertip chain breaks most easily. The locked arms are the hardest. A tight hold is like a solid, a loose hold like a gas.
1.7. Take an iron nail, a piece of chalk and a rubber band. Try to break them by hammering, cutting or stretching. The particles of the nail are held by the strongest force. Chalk breaks. The rubber band stretches.
1.8. Try to cut the stream from a tap with your fingers. The stream does not cut apart completely and stays together, because water particles keep pulling one another. These three activities say that there is a force between particles and that its strength differs.
Worked exampleExample
Question: Arrange oxygen, water and sugar in increasing order of attraction between particles.
Answer: Oxygen is a gas, water is a liquid and sugar is a solid. The increasing order is oxygen < water < sugar.
10-second revision
- Attraction: solid > liquid > gas
- In 1.6 the fingertip chain breaks most easily
- A diver can cut water, not a block of wood
Board tip · BSEBBoard tip
In an increasing order write the weakest first. Oxygen, then water, then sugar.
Board tip · CBSEBoard tip
1.6 is the game, 1.7 is three objects, 1.8 is the tap. All three conclude the same force.
Check your understandingall correct = mastery ★
1
The force of attraction between particles is greatest in —
💡 Hint:
A nail is harder to break than chalk.
Explanation:
The attraction is greatest in a solid.
2
A stream from a tap stays together under the fingers because water particles attract one another.
Explanation:
True — that is the conclusion of Activity 1.8.
3
In increasing order of attraction come oxygen, water and ______.
💡 Hint:
Gas, liquid, then solid.
Explanation:
Sugar. The order is oxygen, water, sugar.
4
A diver cuts through water, but a hand cannot pass through a block of wood. Which property does this show?
Model answer (board format)
It shows the force of attraction between particles. In water the force is weaker, so a diver can cut through. In solid wood the force is much stronger.
Check your answer:
Solid, liquid and gas — Activities 1.9, 1.10, 1.11
ठोस, द्रव और गैस — क्रियाकलाप 1.9, 1.10, 1.11 · Section 1.3 · three states · one picture
The state comes from how the particles are arrangedNotes
Matter around us is in three states: solid, liquid and gas. The differences are in shape, volume, rigidity, flow, compressibility and kinetic energy.
A rubber band changes shape when stretched and returns when the force is removed. Too much force breaks it. It is still a solid. Each crystal of sugar or salt keeps its own shape, whatever the jar. A sponge has tiny holes. Pressing it drives out trapped air, so it compresses, but it is still a solid.
A gas particle hits the wall. That force on a unit area of the wall is the pressure. The smell of the kitchen arrives without your going in, because diffusion of a gas is very fast. Oxygen and carbon dioxide dissolved in water are necessary for aquatic life.
| Property | Solid | Liquid | Gas |
|---|---|---|---|
| Shape | Fixed | Of the vessel | None |
| Volume | Fixed | Fixed | Fills the vessel |
| Compressibility | Negligible | Very small | High |
| Diffusion | Very slow | Faster than a solid | Fastest |
| Attraction | Strongest | In between | Weakest |
Activities 1.9, 1.10 and 1.11 — a pen, 50 mL and three syringesActivity
1.9. Take a pen, a book, a needle and a wooden stick. Trace their shapes in your notebook. They have a definite shape, a clear boundary and a fixed volume. Hammering, pulling or dropping may break them, but they do not take a new shape easily. They are rigid and do not diffuse into one another. Pressing does not shrink them.
1.10. Take water, cooking oil, milk, juice and a cold drink. Mark 50 mL on containers of different shapes with a measuring cylinder. Pour 50 mL of a liquid from one container into another. The volume stays 50 mL and the shape becomes that of the container. Spilt on the floor, it flows. A liquid is not rigid, but it is a fluid. Diffusion of a liquid is faster than that of a solid.
1.11. Take three 100 mL syringes and close the nozzles with rubber corks. Remove the pistons. Leave one syringe empty, that is, with air. Fill the second with water. Fill the third with pieces of chalk. Put a little vaseline on the pistons, insert them and push. The piston of the air syringe goes in most easily. A gas is far more compressible than a solid or a liquid. LPG, hospital oxygen and CNG in vehicles are carried in small cylinders for this reason.
Worked exampleExample
Question: A wooden block has mass 50 g and volume 100 cm³. Find the density.
Formula: density = mass / volume.
Substitution: density = 50 g / 100 cm³ = 0.5 g/cm³.
The density of water is about 1 g/cm³. This block is lighter than water, so it can float. The unit is g/cm³.
10-second revision
- Solid: both shape and volume fixed; compressibility negligible
- Liquid: volume fixed, shape not; gas: neither
- In 1.11 the air piston is pushed in most easily
Board tip · BSEBBoard tip
A sponge, a rubber band and a sugar crystal are all solids. Write a separate reason for each.
Board tip · CBSEBoard tip
A density answer needs the formula, the values and the unit. Only 0.5 is not enough.
Check your understandingall correct = mastery ★
1
Among the three syringes the piston is pushed in most easily in —
💡 Hint:
Activity 1.11.
Explanation:
Air, a gas, is the most compressible.
2
A sponge is not a solid, because it can be compressed.
Explanation:
False — a sponge is a solid. It compresses because air leaves its holes.
3
Density = ______ / volume.
💡 Hint:
In SI, kg/m³.
Explanation:
Mass / volume.
4
When 50 mL of milk is poured into another container —
💡 Hint:
Activity 1.10.
Explanation:
A liquid keeps a fixed volume and takes the shape of the container.
5
Why does a gas exert pressure on the walls of the container? Also write the diffusion difference in one sentence.
Model answer (board format)
Gas particles move fast and at random and hit the wall. This force on a unit area is the pressure. Gases diffuse faster than solids and liquids because the particles are far apart and their speed is high.
Check your answer:
Temperature, melting point and latent heat — Activity 1.12
ताप, गलनांक और गुप्त ऊष्मा — क्रियाकलाप 1.12 · Section 1.4.1 · 273 K · 373 K
The temperature pauses while the state changesNotes
Water exists in all three forms: ice, water and water vapour. Heat a solid and the particles vibrate faster. The heat overcomes the attraction and the particles leave their places to become a liquid. The temperature at which a solid becomes a liquid at atmospheric pressure is the melting point. The melting point tells the strength of the attraction. Melting is also called fusion.
The melting point of ice is 273.16 K. For convenience we write 0°C = 273 K. The temperature does not rise while the ice is melting. This heat is used in changing the state and stays hidden. It is called latent heat. The heat that changes 1 kg of a solid into liquid at the melting point, at atmospheric pressure, is the latent heat of fusion. So particles in water at 0°C have more energy than particles in ice at the same temperature.
Boiling is a bulk process. The boiling point of water is 373 K, because 100 + 273 = 373. The heat that changes 1 kg of liquid into gas at the boiling point is the latent heat of vaporisation. Steam at 373 K has more energy than water at the same temperature.
Activity 1.12 — from 150 g of ice to steamActivity
Take about 150 g of ice in a beaker. Hang a laboratory thermometer so that its bulb touches the ice. Heat on a low flame. Note the temperature when the ice starts melting and the temperature when all the ice has become water. Between the two, the temperature does not rise.
Then put in a glass rod and heat while stirring until the water starts boiling. Watch the thermometer until most of the water has turned to vapour. The reading pauses during boiling too. Both the solid-to-liquid and the liquid-to-gas changes are brought about by temperature. Be careful with the flame and the glass.
Worked exampleExample
Question: Convert 25°C and 300 K to the other scale.
Formula: K = °C + 273, and °C = K − 273.
Substitution: 25°C = 25 + 273 = 298 K.
300 K = 300 − 273 = 27°C.
In the same way 293 K = 20°C and 470 K = 197°C. 373°C = 373 + 273 = 646 K.
10-second revision
- K = °C + 273; ice 273.16 K; water boils at 373 K
- Latent heat is for 1 kg and it does not raise the temperature
- Boiling is a bulk process; Activity 1.12 uses 150 g of ice
Board tip · BSEBBoard tip
Write 273.16 when the melting point is asked. Use 273 when you add or subtract.
Board tip · CBSEBoard tip
Steam and boiling water can be at the same temperature. The difference is latent heat.
Check your understandingall correct = mastery ★
1
The boiling point of water is —
💡 Hint:
100 + 273.
Explanation:
100°C = 373 K.
2
While ice is melting, the temperature of the beaker keeps rising.
Explanation:
False — after the melting point the temperature does not change until all the ice has melted. The heat stays latent.
3
25°C = ______ K.
💡 Hint:
Add 273.
Explanation:
25 + 273 = 298 K.
4
The latent heat of fusion is measured —
💡 Hint:
At atmospheric pressure and the melting point.
Explanation:
It is the heat that changes 1 kg of solid into liquid at the melting point.
5
Convert 470 K to Celsius. Show the formula and the unit.
Model answer (board format)
The formula is °C = K − 273. 470 − 273 = 197. The answer is 197°C.
Check your answer:
6
The physical state of water at 0°C is —
💡 Hint:
This is the melting point.
Explanation:
At 0°C both ice and water can be present. At 25°C it is liquid. At 100°C both liquid and vapour. At 250°C it is a gas.
Pressure and sublimation — Activity 1.13
दाब और ऊर्ध्वपातन — क्रियाकलाप 1.13 · Section 1.4.2 · dry ice · 1 atm
The state can change without a liquid in betweenNotes
Camphor and ammonium chloride become gas directly on heating and settle as a solid on a cold surface. Solid to gas, or gas to solid, with no liquid — that is sublimation. Naphthalene balls disappear with time and leave no solid, for this reason.
Gases become liquid when the pressure is raised and the temperature is lowered. Solid carbon dioxide is stored under high pressure. When the pressure falls to 1 atmosphere it becomes gas directly, with no liquid. That is why it is called dry ice. 1 atm = 1.01 × 10⁵ Pa. Atmospheric pressure at sea level is taken as 1 atm.
Both temperature and pressure decide the state. In the diagram, solid to liquid is fusion, liquid to gas is vaporisation, gas to liquid is condensation and liquid to solid is solidification. Increasing the heat and decreasing the pressure takes a solid straight to a gas. Decreasing the heat and increasing the pressure takes a gas straight to a solid. Both direct paths are sublimation.
Activity 1.13 — a funnel and a cotton plugActivity
Take a little camphor or ammonium chloride. Crush it and put it in a china dish. Place an inverted funnel over the dish. Put a cotton plug on the stem of the funnel so that the vapour does not escape. Heat slowly.
The solid becomes vapour directly and then settles as a solid on the cooler wall of the funnel. No liquid drop appears in between. That is sublimation. Do not hold the hot dish in your hand.
Worked exampleExample
Question: Name A, B, C, D, E and F. A is solid to liquid, B liquid to gas, C gas to liquid, D liquid to solid, E solid to gas and F gas to solid.
Answer: A is fusion, B is vaporisation, C is condensation, D is solidification, E is sublimation and F is sublimation. On E the heat rises and the pressure falls. On F the heat falls and the pressure rises.
10-second revision
- Sublimation: solid ⇌ gas, no liquid in between
- Dry ice is solid CO2; at 1 atm it becomes gas directly
- 1 atm = 1.01 × 10⁵ Pa
Board tip · BSEBBoard tip
The naphthalene answer is sublimation. Do not write melting.
Board tip · CBSEBoard tip
Keep the A to F order of the book diagram: fusion, vaporisation, condensation, solidification, then both direct paths.
Check your understandingall correct = mastery ★
1
Heating camphor slowly gives —
💡 Hint:
Activity 1.13.
Explanation:
Camphor sublimes. The liquid does not come in between.
2
Dry ice first becomes a liquid like water at 1 atm.
Explanation:
False — solid CO2 becomes gas directly when the pressure falls.
3
1 atmosphere = 1.01 × 10⁵ ______.
💡 Hint:
The SI unit of pressure.
Explanation:
Pascal, Pa.
4
Write one way to liquefy atmospheric gases. Also define sublimation.
Model answer (board format)
A gas becomes liquid when the pressure is increased and the temperature is decreased. Sublimation is the change in which a solid becomes gas directly, or a gas becomes solid directly, with no liquid state in between.
Check your answer:
Evaporation and cooling — Activity 1.14
वाष्पीकरण और ठंडक — क्रियाकलाप 1.14 · Section 1.5 · four factors · group model
Leaving from the surface is evaporationNotes
At every temperature some particles have more kinetic energy. Such particles at the surface of a liquid break the attraction and become vapour. This happens below the boiling point too. It is evaporation. Wet clothes dry and uncovered water slowly disappears. In boiling, particles from the whole liquid become vapour. Evaporation is only a surface process.
The rate rises when the surface grows, the temperature rises or the wind becomes faster. The rate falls when humidity rises. At one temperature air cannot hold more than a limit of water vapour. On a rainy day the air already holds more vapour, so drying is slow.
In an open vessel the liquid keeps evaporating. Particles at the surface carry energy away. The remaining liquid and the surroundings supply that energy again, so there is cooling. Acetone or perfume feels cold on the palm. Water is sprinkled on a hot roof because the heat of vaporisation is taken from the surface. In summer a cotton cloth soaks sweat and holds it out to the air. Water seeps through the pores of a matka and evaporates, so the water inside stays cool. A desert cooler cools better on a hot dry day. Tea in a saucer cools sooner because the surface is larger.
Drops on the outside of a glass of ice-cold water are not water leaking from inside. Water vapour in the air loses energy on the cold glass and becomes liquid.
Activity 1.14 and the group model at the endActivity
1.14. Keep 5 mL of water in three places. In a test tube, near a window or under a fan. In an open china dish, near the same window or fan. In an open china dish, inside a cupboard or on a classroom shelf. Note the room temperature. Note the time or the days taken to dry. Repeat these three steps on a rainy day.
The open dish dries sooner than the test tube, because the surface is larger. Near the fan it dries sooner than in the cupboard. On a rainy day all of them dry more slowly. Conclusion: surface, temperature and wind speed raise the rate. Humidity lowers the rate.
Group model. After the numbered activities the book asks for a model. Take a transparent jar, a rubber sheet or a balloon, a string, and chickpeas or dry peas. Put the seeds in the jar. Sew the string to the centre of the sheet and fix it with tape. Stretch the sheet over the mouth of the jar. Move the string up and down, first slowly and then fast. A slow tug is like the vibration of a solid. A fast tug is like the greater motion of a liquid and a gas.
Worked exampleExample
Question: One day water is kept in a test tube, an open dish and a dish under a fan. Write the likely order of drying. What changes on a rainy day?
Answer: The open dish under the fan dries first, then the open dish without the fan, then the test tube. Surface and wind speed raise the rate. On a rainy day the humidity is higher, so evaporation becomes slower in all three.
10-second revision
- Evaporation is at the surface; boiling is in the whole liquid
- Rate: surface, temperature and wind speed raise it; humidity lowers it
- Evaporation causes cooling; the outer drops are condensed vapour
Board tip · BSEBBoard tip
Among the four factors humidity points the other way. Three raise the rate, humidity lowers it.
Board tip · CBSEBoard tip
Do not call the drops on the outside of the glass a leak. They are condensation of vapour from the air.
Check your understandingall correct = mastery ★
1
The rate of evaporation falls when —
💡 Hint:
The other three raise the rate.
Explanation:
Higher humidity lowers the rate. Surface, temperature and wind speed raise the rate.
2
Boiling and evaporation are both processes of particles from the whole liquid.
Explanation:
False — boiling is a bulk process. Evaporation happens only at the surface, below the boiling point.
3
In Activity 1.14 each container has ______ mL of water.
💡 Hint:
Three arrangements.
Explanation:
5 mL.
4
Cotton clothes are comfortable in summer because —
💡 Hint:
The cooling comes from evaporation.
Explanation:
Cotton soaks sweat and holds it out to the air, so evaporation keeps the body cool.
5
Why does a desert cooler cool better on a hot dry day? Also write one reason for tea in a saucer.
Model answer (board format)
On a dry day the humidity is low, so water evaporates faster and the cooling is greater. A saucer has a larger surface, evaporation is faster, and the tea cools soon enough to sip.
Check your answer:
❓ Full question bank — with answers and explanations — 67 questions
Pick a type. The 35 lesson checks are separate — each lesson has as many as its topic needs. All correct earns mastery ★.
BSEB modelpractice · not annual60 tried · 0 correctMultiple choiceMCQ140 tried · 0 correctTrue / falseTrue / false80 tried · 0 correctFill in the blanksFill80 tried · 0 correctMatchMatch20 tried · 0 correctAssertion–reasonAssertion–reason50 tried · 0 correctBalancingBalancing40 tried · 0 correctIdentifyIdentify20 tried · 0 correctShort and longVSA, SA, LA120 tried · 0 correctCBSE-stylenot a PYQ60 tried · 0 correct
No question is marked as a verified past paper. The BSEB set is a model for practice. CBSE items are CBSE-style, not a copy of any year’s paper.
Multiple choice
0/14Pick one option. A wrong try brings a hint.
1
Matter is recognised by —
💡 Hint:
Space and mass.
Explanation:
Anything that has mass and occupies space is matter.
2
The colour of potassium permanganate after 5 to 8 dilutions —
💡 Hint:
Activity 1.2.
Explanation:
The colour grows pale, but it remains. The particles are very small.
3
The smell of hot food travels far because —
💡 Hint:
Diffusion becomes faster with temperature.
Explanation:
Hot particles diffuse faster.
4
The increasing order of attraction is —
💡 Hint:
Gas, liquid, solid.
Explanation:
Oxygen < water < sugar.
5
What is correct about a liquid?
💡 Hint:
50 mL is still 50 mL in another container.
Explanation:
A liquid has a fixed volume and the shape of the container.
6
A lot of CNG fits in a cylinder because —
💡 Hint:
Activity 1.11.
Explanation:
A gas is highly compressible, so it is filled into a small cylinder.
7
Heat supplied while ice melts —
💡 Hint:
The temperature pauses.
Explanation:
This is latent heat. The temperature does not rise until all the ice has melted.
8
300 K is equal to —
💡 Hint:
Subtract 273.
Explanation:
300 − 273 = 27°C.
9
Dry ice is —
💡 Hint:
Gas directly at 1 atm.
Explanation:
Dry ice is solid CO2. At 1 atm it becomes gas with no liquid.
10
Evaporation is faster when —
💡 Hint:
Activity 1.14.
Explanation:
A large surface and a fast wind raise the rate. High humidity lowers it.
11
Drops on the outside of a glass of ice-cold water come from —
💡 Hint:
The water inside does not leak.
Explanation:
Vapour in the air loses energy on the cold glass and becomes liquid.
12
One example of plasma is —
💡 Hint:
An ionised gas.
Explanation:
A fluorescent tube and a neon sign contain plasma. So does the Sun.
13
An iron almirah is a solid at room temperature because —
💡 Hint:
Two reasons are enough.
Explanation:
The shape and volume are fixed and the attraction is strong.
14
Steam burns more than boiling water because —
💡 Hint:
Both can be at 373 K.
Explanation:
The extra latent heat is given to the skin.
True or false
0/81
Love and a smell are both matter because people talk about them.
Explanation:
False — a thought, love and hate are not matter. Air and almonds are matter. The smell of a perfume is diffusion of particles, but hate is not matter.
2
Even 2 mL of Dettol can leave a smell after repeated dilution.
Explanation:
True — the book gives this alternative.
3
A crystal diffuses more slowly in hot water than in cold water.
Explanation:
False — in Activity 1.5 hot water is faster.
4
A rubber band returns to its shape when the force is removed, so it is a solid.
Explanation:
True — too much force can also break it.
5
The latent heat of fusion is defined for 1 kg of solid.
Explanation:
True — at the melting point and atmospheric pressure.
6
The change of O2 into O3 is a result of this chapter.
Explanation:
False — this chapter has no chemical equation. A change of state is physical.
7
Evaporation becomes faster on a rainy day.
Explanation:
False — the rate falls because humidity is higher.
8
The Bose-Einstein condensate is linked to the work of the Indian physicist Satyendra Nath Bose.
Explanation:
True — the calculation around 1920, and the experiment later. This is extra information. The main examination part is the three states.
Fill in the blanks
0/81
The SI unit of volume is the ______.
💡 Hint:
The kilogram is the unit of mass.
Explanation:
The cubic metre. The kilogram is the unit of mass.
2
The beaker in Activity 1.1 is of ______ mL.
💡 Hint:
It is filled about half.
Explanation:
100 mL. It is filled about half.
3
Particles mixing on their own is called ______.
💡 Hint:
It becomes faster with temperature.
Explanation:
Diffusion. It becomes faster when the temperature rises.
4
The boiling point of water is ______ K.
💡 Hint:
100 + 273.
Explanation:
373 K, because 100 + 273 = 373.
5
For convenience 0°C is written as ______ K.
💡 Hint:
The exact value is 273.16 K.
Explanation:
273 K. The exact value is 273.16 K.
6
The other name of solid carbon dioxide is ______.
💡 Hint:
Gas directly at 1 atm.
Explanation:
Dry ice. At 1 atm it becomes gas directly.
7
Evaporation is a ______ phenomenon.
💡 Hint:
Boiling is a bulk phenomenon.
Explanation:
Surface. Boiling is a bulk phenomenon.
8
The SI unit of pressure is the ______.
💡 Hint:
1 atm = 1.01 × 10^5 Pa.
Explanation:
Pascal. 1 atm = 1.01 × 10^5 Pa.
Match
0/21
Match the activity with its main observation.
Column B: A. Colour faster in hot water · B. Air compresses the most · C. Vapour with no liquid · D. The level hardly rises
1. 1.1 salt
2. 1.5 hot-cold
3. 1.11 syringe
4. 1.13 camphor
Explanation:
1.1 the level, 1.5 temperature, 1.11 compressibility, 1.13 sublimation.
2
Match the change with its name.
Column B: A. Fusion · B. Vaporisation · C. Condensation · D. Sublimation
1. Solid to liquid
2. Liquid to gas at boiling point
3. Gas to liquid
4. Solid to gas directly
Explanation:
Fusion, vaporisation, condensation, sublimation.
Assertion–reason
0/5Check both statements, then see whether the reason explains the assertion.
1
Assertion (A): The water level hardly rises when salt dissolves.
Reason (R): Particles of salt move into the spaces between particles of water.
Explanation:
Both are true and R explains A.
2
Assertion (A): Diffusion is faster in hot water.
Reason (R): The attraction of particles in a solid is greater than in a gas.
Explanation:
Both are true, but R does not explain the rate in hot water.
3
Assertion (A): The temperature stays steady while ice melts.
Reason (R): The heat supplied during this time increases the number of particles.
Explanation:
A is true. R is false — the heat is used in changing the state. It does not increase the count of particles.
4
Assertion (A): Evaporation is a bulk process of the whole liquid.
Reason (R): Some particles at the surface become vapour because of higher kinetic energy.
Explanation:
A is false. Evaporation is a surface process. R is true.
5
Assertion (A): Steam at 373 K burns more than water at the same temperature.
Reason (R): Particles in steam carry extra latent heat of vaporisation.
Explanation:
Both are true and R is the correct reason.
Balance the equation
0/4This chapter has no chemical equation. The items below are only coefficient practice. Ice, liquid water and steam are the same substance.
1
This is coefficient practice and not a result of this chapter. A change in the state of water does not make a new substance. Balance H2 + O2 → H2O (blank = 1).
H2 + O2 → H2O
Explanation: 2H2 + O2 → 2H2O
2
Coefficient practice, not an equation of the chapter. Ice, water and steam are all H2O. Still fill the coefficients of H2 + O2 → H2O (blank = 1).
H2 + O2 → H2O
Explanation: 2H2 + O2 → 2H2O
3
A kelvin conversion is not a coefficient. This is a separate practice and not a chemical result of this chapter. Balance H2 + O2 → H2O (blank = 1).
H2 + O2 → H2O
Explanation: 2H2 + O2 → 2H2O
4
The formula does not change in sublimation either. This is coefficient practice, not a result of the chapter. Write the coefficients of H2 + O2 → H2O (blank = 1).
H2 + O2 → H2O
Explanation: 2H2 + O2 → 2H2O
Classify
0/21
Place each item as solid, liquid or gas.
Iron nail
Cooking oil
Air
Sponge
Explanation:
The nail and the sponge are solids. Oil is a liquid. Air is a gas.
2
Place each change as evaporation, boiling or sublimation.
A wet cloth drying at room temperature
All the water becoming steam at 100°C
A naphthalene ball disappearing
Tea in an open saucer cooling
Explanation:
The cloth and the saucer are evaporation at the surface. 100°C is bulk boiling. Naphthalene sublimes.
Very short answer
0/51
Define diffusion in one line.
Model answer (board format)
Diffusion is the spreading of particles of two different substances into each other’s spaces on their own.
Check your answer:
2
What is a melting point?
Model answer (board format)
The temperature at which a solid becomes a liquid at atmospheric pressure is the melting point. The melting point of ice is 273.16 K.
Check your answer:
3
Define the latent heat of fusion.
Model answer (board format)
The latent heat of fusion is the heat required to change 1 kg of a solid into liquid at the melting point at atmospheric pressure.
Check your answer:
4
Write one difference between boiling and evaporation.
Model answer (board format)
Boiling happens in the whole liquid at a fixed temperature. Evaporation happens only at the surface, at any temperature below the boiling point.
Check your answer:
5
Convert 25°C to kelvin.
Model answer (board format)
K = °C + 273 = 25 + 273 = 298 K.
Check your answer:
Short answer
0/41
Compare the arrangement, attraction and compressibility of particles in a solid, a liquid and a gas.
Model answer (board format)
In a solid the particles are close and fixed, the attraction is strongest and compressibility is negligible. In a liquid the particles slide, the attraction is in between and compressibility is very small. In a gas the particles are far apart, the attraction is weakest and compressibility is the greatest.
Check your answer:
2
Convert 293 K and 470 K to Celsius. Show the steps.
Model answer (board format)
°C = K − 273. 293 − 273 = 20°C. 470 − 273 = 197°C.
Check your answer:
3
Write the four factors that change the rate of evaporation and the direction of each.
Model answer (board format)
The rate rises when the surface increases, the temperature rises and the wind speed increases. The rate falls when humidity rises.
Check your answer:
4
Why is water a liquid at room temperature and an iron almirah a solid? Two reasons each.
Model answer (board format)
Water flows and takes the shape of the container, but the volume stays fixed, so it is a liquid. The almirah has a fixed shape and volume and it is rigid, so it is a solid.
Check your answer:
Long answer
0/31
Write the method of Activity 1.12. What is latent heat? Why does ice at 0°C cool more than water at the same temperature? Why does steam burn more?
Model answer (board format)
Put the thermometer bulb in 150 g of ice and heat on a low flame. Note the temperature of melting and the temperature until all the ice has melted. Then stir and boil. The temperature does not rise during the change of state. This hidden heat is latent heat. It is defined for 1 kg. Ice needs the latent heat of fusion to melt, so it cools more. Steam carries extra latent heat of vaporisation, so it burns more.
Check your answer:
2
Write the three characteristics of particles with examples. Use Activities 1.1, 1.3 and 1.7 once each.
Model answer (board format)
There is space between particles: in 1.1 the level does not rise when salt dissolves. Particles keep moving: in 1.3 the smell of a lit incense stick travels far, which is diffusion. Particles attract one another: in 1.7 an iron nail is harder to break than chalk.
Check your answer:
3
Convert 373°C to kelvin. Write the state of water at 25°C, 0°C and 100°C. Give one daily example of sublimation.
Model answer (board format)
K = 373 + 273 = 646 K. At 25°C water is liquid. At 0°C it can be both solid and liquid. At 100°C it can be both liquid and vapour. Naphthalene balls disappear without becoming liquid.
Check your answer:
BSEB model paper · practice
0/6This model set is for practice. It is not a question from any year’s annual examination. Annual questions will be added only when a source page is available.
1
The correct relation for density is —
💡 Hint:
The unit is kg/m³ or g/cm³.
Explanation:
Density = mass / volume.
2
Which of these is sublimation?
💡 Hint:
No liquid in between.
Explanation:
Naphthalene sublimes.
3
100°C = ______ K.
💡 Hint:
Add 273.
Explanation:
373 K. Add 273 to 100.
4
Why does water remain a liquid at room temperature? Two reasons.
Model answer (board format)
Its volume stays fixed but its shape does not, and it flows. The attraction of the particles is enough to hold the volume, not strong enough to fix the shape.
Check your answer:
5
Model practice: this is filling coefficients, not a result of this chapter. Balance H2 + O2 → H2O (blank = 1).
H2 + O2 → H2O
Explanation: 2H2 + O2 → 2H2O
6
Why does evaporation cause cooling? Write one sentence each on any three of acetone, water on a roof, cotton clothes and a matka.
Model answer (board format)
Particles at the surface become vapour by taking energy, and that energy comes from the surroundings, so there is cooling. Acetone leaves by taking energy from the palm. Water on a roof cools the surface by taking the large heat of vaporisation. Cotton soaks sweat and lets it evaporate. Water evaporating through the pores of a matka keeps the water inside cool.
Check your answer:
CBSE-style questions
0/6These are competency-based practice questions. They are not copies of a CBSE paper.
1
A student drops one crystal each into hot and cold water and then stirs. Why is the comparison with Activity 1.5 no longer reliable?
💡 Hint:
The book says do not stir.
Explanation:
Stirring mixes the water by itself, so the rate due to temperature alone is not seen.
2
The density of a block of mass 50 g and volume 100 cm³ is —
💡 Hint:
Mass ÷ volume.
Explanation:
50 / 100 = 0.5 g/cm³.
3
Assertion (A): Water in an open vessel slowly decreases.
Reason (R): Some particles at the surface become vapour even below the boiling point.
Explanation:
Both are true and R explains A as evaporation.
4
Assertion (A): A gas is highly compressible.
Reason (R): The space between particles of a gas is negligible.
Explanation:
A is true. R is false — the space between particles of a gas is the greatest.
5
At summer noon water is sprinkled on the roof and a glass of ice is kept in the room. Why does the roof cool? Where do the drops outside the glass come from?
Model answer (board format)
Water on the roof evaporates and takes the latent heat of vaporisation from the surface, so the roof cools. The drops outside the glass are water vapour from the air, which loses energy on the cold glass and becomes liquid.
Check your answer:
6
A report says water at 0°C and ice at 0°C will cool equally, because the temperature is the same. Where is the mistake? Also write 298 K in Celsius.
Model answer (board format)
The mistake is that ice still needs the latent heat of fusion to melt, so it takes more heat. 298 − 273 = 25°C.
Check your answer:
🏛️ Board exam corner — Bihar Board (BSEB)— CBSE
Switch board with BSEB | CBSE above. The lessons follow the same NCERT chapter.
BSEB model · practiceBoard tip
This page has no verified annual-exam question, because no source page has been added. The model set below is practice in the board pattern.
🏛️ Model questions on one page →
The verified label will be used only when a source page for the question is available.
CBSE-style · competency-based
These are case and assertion-reason practice items. Do not treat them as past CBSE questions.
🔁 Spaced review — today’s questions
Wrong questions return soon; correct ones return after a few days.
🧠 What you learned + equation sheet
What you learned
- Matter has mass and volume. Its particles have space, they move, and they attract one another.
- A solid has a fixed shape and volume. A liquid has a fixed volume and no fixed shape. A gas has neither.
- Diffusion happens on its own and becomes faster on heating.
- Temperature does not rise during a change of state. The hidden heat is latent heat. Remember the 1 kg definition.
- 0°C = 273 K and 100°C = 373 K. In sublimation the liquid state does not come in between.
- Evaporation is a surface process and it causes cooling. The rate falls when humidity rises.
| What | Keep this |
|---|---|
| Melting point of ice | 273.16 K, taken as 273 K |
| Boiling point of water | 373 K, or 100°C |
| Kelvin conversion | K = °C + 273 |
| 1 atmosphere | 1.01 × 10^5 Pa |
| Latent heat | for 1 kg, temperature stays put |
| Evaporation | surface, below boiling point |
The notes are original writing. The textbook was used only for activity order and numbers. “Verified” will be used only on a question that has a source page.