A Journey through States of Water – Short Answer Type Questions
Class 6 Science — Chapter 8: A Journey through States of Water
Content Bank — Topics Covered
States of water, melting, freezing, evaporation, condensation, precipitation, sublimation, water cycle, latent heat, density, experiments and environmental connections.
Basics: States & Definitions (Q1–Q10)
- 1. Name the three states of water.Solid (ice), liquid (water) and gas (water vapour).
- 2. What is melting?Melting is the change of a solid into a liquid on heating.
- 3. Define freezing.Freezing is the change of a liquid into a solid on cooling.
- 4. What is evaporation?Evaporation is the change of liquid into vapour from the surface at any temperature.
- 5. Define condensation.Condensation is the change of vapour into liquid on cooling.
- 6. What is boiling?Boiling is rapid vaporisation that happens throughout a liquid at its boiling point.
- 7. Define sublimation with an example.Sublimation is solid changing directly into gas, e.g., dry ice (solid CO₂) turning into gas.
- 8. What is water vapour?Water vapour is the invisible gaseous form of water in the air.
- 9. What are condensation nuclei?Tiny particles like dust or salt that provide surfaces for vapour to condense and form droplets.
- 10. Define precipitation.Precipitation is water falling from clouds as rain, snow, sleet or hail.
Water Cycle & Processes (Q11–Q20)
- 11. What are the main steps of the water cycle?Evaporation, condensation, precipitation and collection.
- 12. How does transpiration contribute to the water cycle?Transpiration is the release of water vapour from plants, adding moisture to the atmosphere.
- 13. How do clouds form?Clouds form when rising water vapour cools and condenses on condensation nuclei to form droplets.
- 14. Why does evaporation increase on a hot windy day?Higher temperature supplies energy and wind removes humid air, both increasing evaporation rate.
- 15. What causes dew to form?Dew forms when surfaces cool below the dew point and water vapour condenses into droplets.
- 16. What is runoff?Runoff is water that flows over land into rivers and lakes after rainfall.
- 17. What is infiltration?Infiltration is the process of rainwater soaking into the ground and replenishing groundwater.
- 18. Why does boiling point change with altitude?Lower atmospheric pressure at high altitudes lowers the boiling point of water.
- 19. How do clouds cause different types of precipitation?Temperature and updrafts determine whether droplets freeze (snow/hail) or fall as rain.
- 20. What is collection in the water cycle?Collection is water gathering in rivers, lakes and oceans after precipitation.
Changes of State & Energy (Q21–Q30)
- 21. What is latent heat?Latent heat is energy absorbed or released during a change of state without temperature change.
- 22. Why does temperature remain constant during melting?Energy is used as latent heat to change state rather than to raise temperature.
- 23. Give an everyday example of evaporation causing cooling.Sweating — evaporation of sweat cools the body.
- 24. What happens to water molecules during boiling?Molecules gain enough energy to form vapour bubbles that rise through the liquid and escape.
- 25. Why is melting ice at 0°C useful in experiments?It demonstrates latent heat and shows temperature stays constant during state change.
- 26. What is meant by 'heat of fusion'?Heat of fusion is the latent heat required to convert a unit mass of solid to liquid at its melting point.
- 27. What is the 'heat of vaporisation'?Heat of vaporisation is the energy needed to convert a unit mass of liquid to vapour at boiling point.
- 28. Why does steam cause more severe burns than boiling water?Steam carries latent heat and releases extra energy when it condenses on skin, causing more burns.
- 29. Give an example where sublimation is useful.Drying of some frozen foods using sublimation (freeze-drying) preserves them without liquid phase damage.
- 30. How does adding salt to ice help clear roads?Salt lowers the freezing point of water, causing ice to melt at lower temperatures.
Properties of Water & Density (Q31–Q38)
- 31. Why does ice float?Ice has a crystalline structure that makes it less dense than liquid water, so it floats.
- 32. How does water's density change with temperature?Density generally decreases as temperature increases; water is densest near 4°C.
- 33. What is surface tension in water?Surface tension is the cohesive force at the surface that makes it act like a stretched membrane.
- 34. How does capillary action help plants?Capillary action moves water up narrow tubes in plants, aiding water transport from roots to leaves.
- 35. Why is water a good solvent?Water's polarity allows it to dissolve many ionic and polar substances, earning it the title 'universal solvent'.
- 36. What effect do impurities have on freezing point?Impurities (like salt) lower the freezing point and can change melting behaviour.
- 37. Why is the concept of specific heat important (simple answer)?Specific heat tells how much heat is needed to change a substance's temperature, affecting climate and cooling/heating rates.
- 38. How does water's high specific heat affect coastal climates?Water's high specific heat moderates coastal temperatures by absorbing and releasing heat slowly.
Practical Observations & Experiments (Q39–Q45)
- 39. Name a simple experiment to show evaporation.Place two dishes of water — one in sun, one in shade — and observe the dish in sun losing water faster.
- 40. How can you demonstrate condensation in class?Boil water and hold a cool lid above the steam to collect droplets from condensation.
- 41. What observation shows melting involves latent heat?Temperature of ice-water mixture stays at 0°C while ice melts even though heat is being added.
- 42. How would you show that boiling depends on pressure?Measure boiling temperature in a pressure cooker (higher) and at high altitude (lower) to compare.
- 43. What safety rule is important when working with steam?Keep a safe distance and use protective gloves because steam can cause severe burns.
- 44. How to measure evaporation rate simply?Measure water volume loss in a dish over time under controlled conditions (same container, area).
- 45. What should you avoid when handling ice and hot water in experiments?Avoid direct contact to prevent burns and frostbite; use tongs and protective equipment.
Applications & Environmental Connections (Q46–Q50)
- 46. How does the water cycle affect agriculture?It provides rainfall for crops and replenishes groundwater essential for irrigation.
- 47. How does deforestation affect the water cycle?Deforestation reduces transpiration and can alter local rainfall patterns and moisture levels.
- 48. Why is cloud seeding used?Cloud seeding introduces particles to encourage condensation and increase precipitation in drought areas.
- 49. How does urbanisation change runoff and infiltration?Urbanisation increases impermeable surfaces, raising runoff and reducing infiltration, leading to floods and lower groundwater recharge.
- 50. Why is understanding states of water important for everyday life?It explains weather, water management, cooking, safety with steam/ice, and many natural processes that affect daily living.
Note: These 50 short answer questions and answers are prepared strictly according to the NCERT Class 6 Science syllabus for Chapter 8 and are ideal for CBSE exam revision and classroom practice.