Chapter 8 A Journey through States of Water Class 6 Extra Questions and Answers Science Curiosity

Q15. Why do clothes dry faster in sunlight?
Ans:- Sunlight provides heat which increases the rate of evaporation, so clothes dry faster.

Q16. Why do clothes dry faster on a windy day?
Ans:- Wind removes water vapour from the surface of clothes, increasing evaporation rate.

Q17. Why does water in a plate evaporate faster than water in a bottle cap?
Ans:- The plate has a larger surface area exposed to air, so water evaporates faster.

Q18. Write the factors that affect the rate of evaporation.
Ans:- The factors that affect the rate of evaporation are following:-

• Surface area: Evaporation increases when the surface area is large because more liquid is exposed to air.
  When the surface area is small, evaporation becomes slow.

• Temperature: Higher temperature gives more energy to liquid particles, so evaporation increases.
  At lower temperature, particles have less energy and evaporation decreases.

• Wind speed: High wind speed carries away water vapour from the surface, increasing evaporation.
  Low wind speed allows vapour to stay near the surface, slowing evaporation.

• Humidity: When humidity is low, air can hold more water vapour, so evaporation is faster.
  High humidity means air already has much vapour, so evaporation slows down.

Q19. What is the cooling effect of evaporation?
Ans:- Evaporation absorbs heat from surroundings, which causes cooling.

Q20. Why does sweat cool our body?
Ans:- Sweat absorbs heat from our skin when it evaporates, making us feel cooler.

Q21. Why does an earthen pot (matka) keep water cool?
Ans:- Water seeps through tiny pores of the matka and evaporates. Evaporation absorbs heat from the water, keeping it cool.

Q22. Why do hands feel cool after applying sanitizer?
Ans:- Sanitiser evaporates quickly and absorbs heat from the skin, causing a cooling effect.

Q23. How are clouds formed?
Ans:- Water vapour rises into the atmosphere, cools, and condenses around dust particles forming tiny water droplets, which make clouds.

Q24. What role do dust particles play in cloud formation?
Ans:- Dust particles act as surfaces for water vapour to condense around, helping cloud formation.

Q25. How does rain occur?
Ans:- Tiny droplets in clouds combine to form bigger drops. When drops become heavy, they fall as rain.

Q26. Why does water vapour rise up in the atmosphere?
Ans:- Water vapour is lighter than air, so it rises upward.

Q27. What is the water cycle?
Ans:- The water cycle is the continuous movement of water between Earth and the atmosphere through evaporation, condensation, and precipitation.

Q28. Write any three steps of the water cycle.
Ans:- 1. Evaporation
2. Condensation
3. Rainfall (Precipitation)

Q29. When does water fall as snow or hail?
Ans:- Water falls as snow or hail under special cold conditions, usually in winter or thunderstorms.

Q30. Why is only a small amount of Earth’s water fit for use?
Ans:- Most water on Earth is salty in oceans. Only a small part is fresh and usable for humans, plants, and animals.

Q31. Why is it important to save water?
Ans:- To avoid shortages, meet increasing demand, and ensure water availability for future generations.

Q32. Explain in short: “Water is our responsibility before it is our right.”
Ans:- We must protect and conserve water before using it freely. Responsible use ensures enough clean water for everyone.

Q33. What is precipitation?
Ans: Falling of water from clouds as rain, snow, or hail is called precipitation.

Q34. What is melting?
Ans: Melting is the process in which a solid changes into liquid on heating.

Q35. What is freezing?
Ans: Freezing is the process in which a liquid changes into solid on cooling.

Q36. Are melting and freezing reversible processes?
Ans: Yes, melting and freezing are reversible processes.

Q37. Explain the water cycle, including evaporation, condensation and precipitation.
Ans: The water cycle is a continuous process that describes the movement of water within the Earth’s atmosphere and surface. It involves several key processes:

1. Evaporation: Evaporation is the process by which water from rivers, lakes, oceans, ponds, and wet surfaces changes into water vapourdue to heat from the Sun. This water vapour rises up into the atmosphere.
2. Condensation: As the water vapour rises higher, it cools down. On cooling, the water vapour changes back into tiny water droplets. This process is called condensation. These tiny droplets collect together to form clouds.
3. Precipitation: When the water droplets in clouds become too heavy, they fall back to the Earth due to gravity. This falling of water from clouds in the form of rain, snow, or hailis called precipitation.

After precipitation, water collects in rivers, lakes, oceans, and also seeps into the ground as groundwater. From there, it again evaporates, and the cycle continues.

The water cycle is a never-ending process that ensures the continuous supply of fresh water on Earth and supports all forms of life.

Q38. Describe an experiment to demonstrate the process of evaporation and its effect on cooling.

Ans: Aim: To demonstrate the process of evaporation and show that evaporation causes cooling.

Materials Required

• Water (or hand sanitiser)
• Two hands (or a thermometer, if available)

Procedure

• 1.Take a small amount of water or hand sanitiser.
• 2.Apply it on the palm of one hand. Keep the other hand dry.
• 3.Blow air over both hands or stand under a fan.
• 4.Observe the sensation on both hands carefully.

Observation

• The wet hand feels coolerthan the dry hand.

Explanation

The water or sanitiser on the hand evaporates by taking heat from the skin.
This loss of heat causes a cooling effect on the wet hand.

Conclusion

Evaporation absorbs heat from the surroundings, resulting in cooling. This proves that evaporation causes a cooling effect.

Precaution

• Ensure both hands are exposed to air equally for accurate observation.