A Journey through States of Water – Important Questions and Answers
Premium CBSE Class 6 Science revision post based on the chapter A Journey through States of Water. Includes evaporation, condensation, melting, freezing, three states of water, water vapour, humidity, cooling effect, clouds, rain, water cycle, case studies, HOTS questions, diagram-based questions, FAQs, and an interactive quiz.
Short Introduction
Water is one of the most important substances on Earth. We see it as ice, liquid water and water vapour. These are the three states of water. Water changes its state on heating or cooling. This chapter explains how water evaporates, condenses, freezes and melts. It also explains why droplets appear on a cold glass, why clothes dry faster in sunlight and wind, how evaporation causes cooling, how clouds give rain, and how water keeps moving through the water cycle.
Chapter Overview
States of Water
Water exists as solid ice, liquid water and gaseous water vapour.
Evaporation
The process of conversion of water into water vapour is called evaporation.
Condensation
The process of conversion of water vapour into liquid water is called condensation.
Melting and Freezing
Melting changes solid into liquid, while freezing changes liquid into solid.
Cooling Effect
Evaporation produces cooling, as seen in earthen pots, sweating and sanitiser on hands.
Water Cycle
Water evaporates, forms clouds by condensation, falls as rain, hail or snow, and returns to water bodies.
Important Concept Flow
Conversion of solid ice into liquid water is called melting.
Conversion of liquid water into vapour is called evaporation.
Conversion of water vapour into liquid water is called condensation.
Conversion of liquid water into solid ice is called freezing.
The continuous movement of water between Earth’s surface and atmosphere is called the water cycle.
Important Keywords with Meanings
| Keyword | Meaning |
|---|---|
| State | A form in which a substance exists, such as solid, liquid or gas. |
| Solid | A state of matter with fixed shape; ice is solid water. |
| Liquid | A state that flows and takes the shape of its container; water is a liquid. |
| Gas | A state that spreads in the entire available space; water vapour is gaseous water. |
| Water vapour | Water in gaseous state, usually invisible in air. |
| Steam | Water vapour, some part of which condenses into visible tiny water droplets. |
| Evaporation | The process of conversion of water into its vapour state. |
| Condensation | The process of conversion of water vapour into liquid water. |
| Melting | The process of conversion of a solid into liquid state. |
| Freezing | The process of conversion of liquid into solid state. |
| Humidity | The amount of water vapour present in air. |
| Cooling effect | The cooling produced when evaporation takes place. |
| Dew drops | Water droplets formed when water vapour condenses on cold surfaces, commonly seen in the morning. |
| Clouds | Tiny water droplets formed by condensation of water vapour in air. |
| Rain | Water drops that fall from clouds when they become heavy. |
| Hail | Ice pieces that fall from clouds under special conditions. |
| Snow | Frozen water falling from clouds under cold conditions. |
| Water cycle | The circulation of water between Earth’s surface and the atmosphere. |
| Atmosphere | The thin layer of air surrounding Earth. |
| Groundwater | Water present below the surface of Earth. |
| Ocean | A large body of salty water covering most of Earth’s surface. |
| Pot-in-pot cooler | A simple cooling model using two earthen pots, sand and water. |
| Matka | An earthen pot used to keep water cool. |
| Surahi | A clay pot used in summer to keep water cool. |
| Atmospheric Water Generator | A machine that collects water from humid air by cooling and condensation. |
Very Short Answer Questions
1. What are the three states of water?
Answer: The three states of water are solid, liquid and gas.
2. What is water in solid state called?
Answer: Water in solid state is called ice.
3. What is water in gaseous state called?
Answer: Water in gaseous state is called water vapour.
4. Does ice flow like water?
Answer: No, ice does not flow like water.
5. Does liquid water have a fixed shape?
Answer: No, liquid water does not have a fixed shape.
6. What is evaporation?
Answer: Evaporation is the process of conversion of water into water vapour.
7. Does evaporation occur only on heating?
Answer: No, evaporation takes place continuously, even at room temperature.
8. Give one example of evaporation.
Answer: Drying of wet clothes is an example of evaporation.
9. What is condensation?
Answer: Condensation is the process of conversion of water vapour into liquid water.
10. Why do water droplets form on a cold glass tumbler?
Answer: Water vapour in air condenses on the cold surface of the glass.
11. What is humidity?
Answer: Humidity is the amount of water vapour present in air.
12. What is melting?
Answer: Melting is the conversion of solid into liquid state.
13. What is freezing?
Answer: Freezing is the conversion of liquid into solid state.
14. What happens when ice is heated?
Answer: Ice melts and changes into liquid water.
15. What happens when water is kept in a freezer?
Answer: Water freezes and changes into ice.
16. Which evaporates faster: water in a plate or water in a bottle cap?
Answer: Water in a plate evaporates faster because it has a larger exposed area.
17. Does water evaporate faster in sunlight or shade?
Answer: Water evaporates faster in sunlight.
18. Does wind increase evaporation?
Answer: Yes, wind or air movement increases evaporation.
19. Why do clothes dry slowly on rainy days?
Answer: Clothes dry slowly on rainy days because humidity is high and evaporation is slow.
20. Why does water in a matka become cool?
Answer: Water seeps through the earthen pot and evaporates, producing a cooling effect.
21. What are clouds made of?
Answer: Clouds are made of tiny water droplets.
22. Around what do tiny water droplets form in clouds?
Answer: They form around dust particles.
23. What is the water cycle?
Answer: The circulation of water between Earth’s surface and atmosphere is called the water cycle.
24. Why should we use water wisely?
Answer: Only a small portion of Earth’s water is fit for use, so we should avoid wasting it.
Short Answer Questions
1. Are ice and water different substances?
Answer: No, ice and water are not different substances. They are two different states of the same substance. Ice is the solid state of water, while ordinary water is the liquid state.
2. Why does water disappear from puddles after rain?
Answer: Water from puddles may disappear due to evaporation and seeping into the ground. Some water changes into water vapour, and some may go into the soil.
3. Why does water on a steel plate disappear after some time?
Answer: Water on a steel plate does not seep through the plate. It slowly changes into water vapour by evaporation and disappears from the plate.
4. Why is water vapour usually invisible?
Answer: Water vapour is water in gaseous state and is usually invisible. Steam may look visible because some part of the water vapour condenses into tiny water droplets.
5. Why do droplets appear on the outside of a glass containing ice-cold water?
Answer: Water vapour present in the air touches the cold outer surface of the glass and condenses into water droplets. These droplets do not come from inside the glass.
6. Why are dew drops seen more commonly in the morning?
Answer: In the morning, surfaces such as leaves are cool. Water vapour in air comes in contact with these cold surfaces and condenses into dew drops.
7. How can we prove that water droplets on a cold tumbler are not due to seeping?
Answer: Mark the water level inside the tumbler. If droplets appear outside but the inside water level does not decrease, it shows that water is not seeping out. The droplets are due to condensation.
8. Write two differences between ice and water.
Answer: Ice has a fixed shape and does not flow. Water does not have a fixed shape and flows from one place to another.
9. Write two properties of water vapour.
Answer: Water vapour has no fixed shape and spreads in the entire available space. It is present in air around us, even at room temperature.
10. How does increasing exposed area affect evaporation?
Answer: Increasing exposed area makes evaporation faster. Water in a plate evaporates faster than the same amount of water in a bottle cap because more surface is exposed to air.
11. How does sunlight affect evaporation?
Answer: Sunlight increases temperature and supplies heat. Therefore, water evaporates faster in sunlight than in shade.
12. How does wind affect drying of clothes?
Answer: Wind increases movement of air and removes water vapour from near the clothes. This makes evaporation faster and clothes dry quickly.
13. Why do clothes dry slowly on rainy days?
Answer: On rainy days, the amount of water vapour in air is high. Due to high humidity, evaporation becomes slow, so clothes dry slowly.
14. Why do we feel cool under a fan when sweating?
Answer: The fan increases air movement and helps sweat evaporate faster from our skin. Evaporation takes heat from our body and produces a cooling effect.
15. How do clouds give rain?
Answer: Water vapour rises and reaches cooler regions. It condenses around dust particles to form tiny droplets. Many droplets join and become heavy, then fall as rain.
Long Answer Questions
1. Explain the three states of water with their properties.
Answer: Water exists in three states: solid, liquid and gas.
- Solid state: Water in solid state is ice. Ice has a fixed shape. It does not flow or spread like water.
- Liquid state: Water in liquid state flows and takes the shape of the container. It has fixed volume but no fixed shape.
- Gaseous state: Water in gaseous state is water vapour. It has no fixed shape and spreads in the entire available space.
2. Explain evaporation with examples.
Answer: Evaporation is the process of conversion of water into water vapour. It takes place continuously, even at room temperature. Examples of evaporation include drying of wet clothes, drying of a mopped floor, drying of sweat from the body, disappearance of water from puddles and disappearance of hand sanitiser when rubbed on hands. When water is sprinkled on a hot pan, it quickly changes into steam due to rapid evaporation.
3. Explain condensation with examples.
Answer: Condensation is the process of conversion of water vapour into liquid water. When water vapour present in air touches a cold surface, it changes into tiny water droplets. Examples include water droplets on the outside of a glass containing ice-cold water, dew drops on plants in the morning, and water drops on the inner side of a steel plate kept over boiling water. Condensation is also important in cloud formation.
4. Explain melting and freezing.
Answer: Melting is the process of conversion of a solid into liquid state. When ice is heated or kept outside the freezer, it melts and changes into liquid water. Freezing is the process of conversion of liquid into solid state. When water is kept in a cold environment such as a freezer, it freezes and changes into ice. Other substances such as wax, ghee, oil and coconut oil can also change state on heating or cooling.
5. Differentiate between evaporation and condensation.
| Evaporation | Condensation |
|---|---|
| Liquid water changes into water vapour. | Water vapour changes into liquid water. |
| It happens from the surface of water. | It happens when water vapour touches a cold surface. |
| It causes cooling effect. | It forms droplets, dew, clouds or rain. |
| Examples: drying clothes, drying sweat, disappearing puddles. | Examples: droplets on cold glass, dew drops, cloud formation. |
6. What factors affect the rate of evaporation?
Answer: The rate of evaporation depends on several conditions:
- Exposed area: Larger exposed area increases evaporation. Water in a plate evaporates faster than water in a cap.
- Temperature: Evaporation is faster on a hot sunny day than on a cold day.
- Air movement: Wind or fan increases evaporation. Clothes dry faster on a windy day.
- Humidity: Evaporation is slower when humidity is high, such as on rainy days.
7. Explain cooling effect due to evaporation.
Answer: During evaporation, water takes heat from its surroundings. This causes cooling. Water stored in an earthen pot becomes cool because a small amount of water seeps through the pores of the pot and evaporates from the outer surface. Sweat cools our body when it evaporates. We also feel cool when sanitiser evaporates from our hands. Sprinkling water on the floor or roof in summer also cools the surface due to evaporation.
8. Explain how a pot-in-pot cooler works.
Answer: A pot-in-pot cooler is made using two earthen pots of different sizes. The smaller pot is placed inside the larger pot. The gap between the two pots is filled with sand and water is poured into the sand. A lid or wet jute sack is used to cover the top. Water from the moist sand evaporates slowly and produces a cooling effect. This keeps the inner pot cool and helps vegetables and fruits remain fresh for some time without electricity.
9. Explain how clouds form and give rain.
Answer: Water from oceans, lakes, rivers and land evaporates and becomes water vapour. Water vapour is lighter than air and rises in the atmosphere. As it goes higher, the air becomes cooler. At certain heights, water vapour condenses around dust particles and forms tiny water droplets. These droplets float in air as clouds. When many droplets join and become heavy, they fall as rain. Under special conditions, water may fall as hail or snow.
10. Explain the water cycle.
Answer: The circulation of water between Earth’s surface and the atmosphere is called the water cycle. Water from oceans, rivers, lakes and the Earth’s surface evaporates into the atmosphere as water vapour. The water vapour cools and condenses to form clouds. Clouds give rain, hail or snow. The water then flows into rivers, lakes, groundwater and oceans. This process continues again and again. The water cycle is essential for life on Earth.
Case-Study Based Questions
Case Study 1: Ice in Lemonade
Aavi and Thirav observe ice cubes in lemonade. Thirav feels that ice and water may be different substances because ice is hard and water flows.
Q1. Are ice and water different substances?
Answer: No, ice and water are different states of the same substance.
Q2. What happens when ice is left at room temperature?
Answer: It melts and changes into liquid water.
Q3. What is the process called?
Answer: Melting.
Case Study 2: Water on a Steel Plate
A tablespoon of water is kept on a steel plate. After some time, the water disappears, but it does not seep through the plate.
Q1. Where did the water go?
Answer: It changed into water vapour by evaporation.
Q2. What is evaporation?
Answer: Evaporation is the conversion of water into water vapour.
Q3. Give another example of evaporation.
Answer: Drying of wet clothes.
Case Study 3: Cold Glass Tumbler
A glass tumbler containing cold water and ice cubes is left undisturbed. After a few minutes, water droplets appear on the outside of the glass.
Q1. Where do the droplets come from?
Answer: They come from water vapour present in air.
Q2. Which process forms these droplets?
Answer: Condensation.
Q3. How can we prove the water is not seeping out?
Answer: Mark the water level inside the glass. If the level does not fall, water is not seeping out.
Case Study 4: Drying Clothes
Two wet clothes are dried. One is kept in sunlight and wind, while the other is kept in a humid room.
Q1. Which cloth will dry faster?
Answer: The cloth kept in sunlight and wind will dry faster.
Q2. Why does wind help?
Answer: Wind increases air movement and speeds up evaporation.
Q3. Why is drying slow in a humid room?
Answer: Air already contains much water vapour, so evaporation becomes slow.
Case Study 5: Clouds and Rain
Water vapour rises in the atmosphere. At higher levels, it becomes cool and forms tiny droplets around dust particles. Later, rain falls.
Q1. Which process forms tiny droplets?
Answer: Condensation.
Q2. What are clouds made of?
Answer: Clouds are made of tiny water droplets.
Q3. When does rain fall?
Answer: Rain falls when many droplets join, become heavy and fall down.
Assertion-Reason Questions
Choose the correct option:
A. Both Assertion and Reason are true and Reason is the correct explanation.
B. Both Assertion and Reason are true but Reason is not the correct explanation.
C. Assertion is true but Reason is false.
D. Assertion is false but Reason is true.
1. Assertion: Ice and water are the same substance. Reason: Ice and water are two different states of water.
Answer: A
2. Assertion: Water flows but ice does not. Reason: Water is a liquid and ice is a solid.
Answer: A
3. Assertion: Water vapour is usually invisible. Reason: Steam is visible because of tiny water droplets.
Answer: B
4. Assertion: Evaporation takes place only at boiling point. Reason: Evaporation can occur even at room temperature.
Answer: D
5. Assertion: Water droplets appear on the outside of a cold glass due to condensation. Reason: Water vapour in air changes into liquid water on a cold surface.
Answer: A
6. Assertion: Larger exposed area increases evaporation. Reason: Water in a plate evaporates faster than water in a bottle cap.
Answer: A
7. Assertion: Clothes dry slowly on rainy days. Reason: Humidity is high on rainy days.
Answer: A
8. Assertion: Evaporation causes cooling. Reason: Evaporation takes heat from surroundings.
Answer: A
9. Assertion: Clouds are formed only from smoke. Reason: Water vapour condenses around dust particles to form tiny droplets.
Answer: D
10. Assertion: The water cycle is important for life. Reason: It circulates water between Earth’s surface and atmosphere.
Answer: A
Competency-Based and Critical Thinking / HOTS Questions
1. Why does natural grass feel cooler than green plastic grass?
Answer: Natural grass contains water and allows evaporation. Evaporation produces cooling. Plastic grass does not support such evaporation, so the area around it feels warmer.
2. Why does a fan help dry wet clothes even though it gives a cooling sensation?
Answer: A fan increases air movement and removes water vapour from around the clothes. This speeds up evaporation, so clothes dry faster.
3. Why does sanitiser feel cool on the hand?
Answer: Sanitiser evaporates quickly. During evaporation, it takes heat from the hand, so the hand feels cool.
4. Why is sludge from drains kept in heaps for a few days before transportation?
Answer: Some water evaporates from the sludge, making it drier and lighter. This reduces transport cost and makes handling safer.
5. Why does water evaporate faster from a plate than from a cap?
Answer: A plate provides a larger exposed surface area. More water surface is in contact with air, so evaporation is faster.
6. Why does the mass of a cold glass tumbler increase during the condensation activity?
Answer: Water vapour from the air condenses on the cold surface of the glass and adds extra water droplets outside, increasing the mass shown on the balance.
7. Why does the water level inside a cold glass not decrease even when droplets appear outside?
Answer: The outside droplets are formed from water vapour present in air. They are not formed by water seeping out from inside the glass.
8. Why do clouds need dust particles for formation?
Answer: Tiny dust particles provide surfaces around which water vapour condenses to form tiny water droplets. These droplets together form clouds.
9. How can you cool a hot two-wheeler seat parked in the sun?
Answer: Sprinkle water on the seat and allow it to evaporate. Evaporation removes heat and cools the seat. Wiping with a wet cloth can also help.
10. Why is the statement “Water is our responsibility before it is our right” important?
Answer: Only a small portion of water on Earth is fit for direct use. As population and demand increase, water shortage becomes serious. Therefore, we must use water wisely, avoid wastage and keep water bodies clean.
Diagram-Based Questions
Diagram 1: Three States of Water
Solid
Ice
Fixed shape
Liquid
Water
Flows
Gas
Water vapour
Spreads everywhere
Question: Which state of water has fixed shape?
Answer: Ice, the solid state of water, has fixed shape.
Diagram 2: Change of States
Question: Which process changes water vapour into liquid water?
Answer: Condensation.
Diagram 3: Cold Glass and Condensation
Question: Do these droplets come from inside the glass?
Answer: No, they come from water vapour present in air.
Diagram 4: Factors Affecting Evaporation
Faster evaporation
Faster evaporation
Faster evaporation
Slower evaporation
Question: Why do clothes dry slowly on rainy days?
Answer: Because humidity is high and evaporation becomes slow.
Diagram 5: Water Cycle
Question: What is the continuous movement of water called?
Answer: The water cycle.
Quick Revision Box
- Ice and water are different states of the same substance.
- Water exists as solid, liquid and gas.
- Ice is solid water.
- Liquid water flows and takes the shape of its container.
- Water vapour is gaseous water and spreads in air.
- Evaporation is conversion of water into water vapour.
- Evaporation occurs even at room temperature.
- Condensation is conversion of water vapour into liquid water.
- Melting is conversion of solid into liquid.
- Freezing is conversion of liquid into solid.
- Water droplets on a cold glass are due to condensation.
- Dew drops form due to condensation on cold surfaces.
- Water in a plate evaporates faster than water in a cap.
- Sunlight and heat increase evaporation.
- Wind increases evaporation.
- High humidity slows evaporation.
- Evaporation causes cooling effect.
- Matka water becomes cool due to evaporation.
- Clouds form when water vapour condenses around dust particles.
- Rain falls when cloud droplets join and become heavy.
- Under special conditions, water may fall as hail or snow.
- The circulation of water between Earth’s surface and atmosphere is the water cycle.
- Only a small portion of Earth’s water is fit for use.
- We should use water wisely and avoid wasting it.
Important Exam Tips
Interactive Quiz
Choose the correct answer and click submit.
Frequently Asked Questions
1. What are the three states of water?
The three states of water are solid ice, liquid water and gaseous water vapour.
2. What is evaporation?
Evaporation is the process of conversion of water into its vapour state.
3. What is condensation?
Condensation is the process of conversion of water vapour into liquid water.
4. Why do droplets form on a cold glass?
Water vapour in air comes in contact with the cold glass surface and condenses into water droplets.
5. What is melting?
Melting is the process of conversion of a solid into liquid state.
6. What is freezing?
Freezing is the process of conversion of liquid into solid state.
7. What factors increase evaporation?
Large exposed area, high temperature and greater air movement increase evaporation.
8. Why does evaporation cause cooling?
Evaporation takes heat from the surroundings, so it produces cooling.
9. How do clouds form?
Clouds form when water vapour condenses into tiny water droplets around dust particles in cooler air.
10. What is the water cycle?
The water cycle is the continuous circulation of water between Earth’s surface and the atmosphere.
Final Conclusion
The chapter A Journey through States of Water teaches that water can exist as ice, liquid water and water vapour. It changes state through melting, freezing, evaporation and condensation. These processes explain many daily life observations such as drying clothes, droplets on a cold glass, cool water in an earthen pot, cloud formation and rain. The chapter also reminds us that usable water is limited, so we must use water wisely and keep water bodies clean.
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