A Journey Through States of Water — Class 6 Science NCERT Solutions (Free)
Free step-by-step NCERT solutions for Class 6 Science chapter "A Journey Through States of Water" — 8 important questions with detailed answers for CBSE board exam preparation.
TL;DR: Free step-by-step NCERT solutions for Class 6 Science chapter "A Journey Through States of Water" — 8 important questions with detailed answers for CB…
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NCERT Solutions for Class 6 Science — A Journey Through States of Water. Step-by-step answers to all 8 textbook questions from this chapter, written for CBSE board preparation and free to use.
A Journey Through States of Water — All 8 Questions Solved
Q1. What are the three states of matter? Give examples of water in each state.
The three states of matter are:
- Solid: Ice (water in frozen form)
- Liquid: Water (water in liquid form at room temperature)
- Gas: Water vapour (water in gaseous form when heated)
Water naturally exists in all three states on Earth.
Q2. What is evaporation? Explain with an example.
Evaporation is the process by which a liquid changes into a gas. It occurs when liquid water is heated, and water molecules gain energy to escape into the air as water vapour. Examples include wet clothes drying on a clothesline, water evaporating from a puddle in sunshine, and sweat evaporating from our skin.
Q3. What is condensation? How is it different from evaporation?
Condensation is the process by which a gas changes into a liquid when cooled. It is the reverse of evaporation. In evaporation, heat is absorbed and a liquid becomes a gas. In condensation, heat is released and a gas becomes a liquid. Example: water vapour in air condenses on cool mirror surfaces as water droplets.
Q4. Describe the water cycle with its main processes.
The water cycle involves four main processes:
- Evaporation: Water from oceans, lakes, and rivers evaporates due to sun's heat
- Condensation: Water vapour cools and forms clouds in the atmosphere
- Precipitation: Water falls as rain, snow, or sleet
- Collection: Water collects in oceans, lakes, rivers, and soil, and the cycle repeats
Q5. What is melting? How is it different from evaporation?
Melting is the process by which a solid changes into a liquid when heated. Evaporation is when a liquid changes into a gas. Melting occurs at a specific temperature (0°C for ice), while evaporation can occur at any temperature. Melting produces liquid, evaporation produces gas.
Q6. What is freezing? Give real-life examples.
Freezing is the process by which a liquid changes into a solid when cooled. It is the reverse of melting. Examples include water freezing into ice at 0°C in winters, formation of frost on leaves during cold nights, and ice cream becoming solid when cooled in a freezer.
Q7. Why does wet clothing dry faster on a hot day than on a cold day?
On a hot day, water in wet clothing receives more heat energy from the sun and air. This energy enables more water molecules to overcome intermolecular forces and escape as water vapour, increasing the rate of evaporation. On a cold day, there is less heat energy, so evaporation occurs slowly.
Q8. Explain why water vapour is invisible, but clouds are visible.
Water vapour is a gas with molecules too small to scatter light, making it invisible. Clouds form when water vapour condenses into tiny liquid water droplets around dust particles in the atmosphere. These droplets are large enough to scatter sunlight, making clouds visible to our eyes.
A Journey Through States of Water — Practice MCQs with Answers
Attempt these 20 multiple-choice questions after working through the solutions above. Each carries the correct option and the reasoning behind it, so a wrong answer tells you which idea to revisit.
MCQ 1. Which of the following is NOT a state of water?
- A. Solid
- B. Liquid
- C. Gas
- D. Plasma
Answer: D. Plasma — Water primarily exists in three common states on Earth: solid (ice), liquid (water), and gas (water vapour). Plasma is another state of matter, but not a typical state of water in our environment.
MCQ 2. What is the solid form of water commonly known as?
- A. Steam
- B. Ice
- C. Cloud
- D. Rain
Answer: B. Ice — Ice is the solid state of water, formed when liquid water freezes at 0°C or below.
MCQ 3. When ice changes into water, what process is taking place?
- A. Evaporation
- B. Condensation
- C. Melting
- D. Freezing
Answer: C. Melting — Melting is the process where a solid substance changes into its liquid state, typically due to an increase in temperature.
MCQ 4. What is the invisible gaseous form of water present in the air called?
- A. Fog
- B. Cloud
- C. Water vapour
- D. Dew
Answer: C. Water vapour — Water vapour is the gaseous state of water, which is invisible to the naked eye, and is a crucial component of the Earth's atmosphere.
MCQ 5. Which of these factors would speed up the process of evaporation?
- A. Increasing humidity
- B. Decreasing temperature
- C. Increasing surface area
- D. Reducing wind speed
Answer: C. Increasing surface area — Evaporation rate increases with higher temperature, larger surface area, increased wind speed, and lower humidity.
MCQ 6. You observe tiny water droplets forming on the outer surface of a glass containing chilled water. This phenomenon is an example of:
- A. Evaporation
- B. Freezing
- C. Condensation
- D. Melting
Answer: C. Condensation — The cold surface of the glass cools down the water vapour in the surrounding air, causing it to change from an invisible gas back into tiny liquid water droplets, which is condensation.
MCQ 7. Which process is primarily responsible for the formation of clouds in the sky?
- A. Evaporation
- B. Condensation
- C. Precipitation
- D. Freezing
Answer: B. Condensation — Clouds form when water vapour in the air rises, cools, and condenses into tiny water droplets or ice crystals around dust particles in the atmosphere.
MCQ 8. What is the main source of energy that drives the water cycle on Earth?
- A. Earth's core
- B. Moon
- C. Sun
- D. Wind
Answer: C. Sun — The Sun's energy heats water on Earth's surface, causing it to evaporate and initiating the continuous process of the water cycle.
MCQ 9. When water is kept in a freezer and turns into ice, this process is known as:
- A. Melting
- B. Evaporation
- C. Freezing
- D. Condensation
Answer: C. Freezing — Freezing is the process by which a liquid changes into a solid when its temperature is lowered to its freezing point.
MCQ 10. On a hot, sunny, and windy day, clothes typically dry faster. Which factor primarily contributes to this faster drying, in addition to temperature?
- A. Humidity
- B. Wind
- C. Pressure
- D. Light
Answer: B. Wind — Wind carries away the water vapour that evaporates from the wet clothes, reducing the humidity directly above them and allowing more water to evaporate faster.
MCQ 11. Rain, snow, and hail are all different forms of which process in the water cycle?
- A. Evaporation
- B. Condensation
- C. Collection
- D. Precipitation
Answer: D. Precipitation — Precipitation is any form of water that falls from the atmosphere to the Earth's surface, including rain, snow, sleet, or hail.
MCQ 12. Which state of water takes the shape of the container it is poured into, but maintains a definite volume?
- A. Solid
- B. Liquid
- C. Gas
- D. Plasma
Answer: B. Liquid — Liquid water has a definite volume but no definite shape, meaning it will always take the shape of its container.
MCQ 13. How does dew typically form on grass and other surfaces in the early morning?
- A. Water from the soil rises up onto the grass
- B. It is a result of light rainfall overnight
- C. Water vapour in the air condenses on cool surfaces
- D. Ice melts and forms water droplets on the grass
Answer: C. Water vapour in the air condenses on cool surfaces — As surfaces like grass cool down overnight, the water vapour in the surrounding air loses heat and condenses onto these cool surfaces, forming tiny water droplets known as dew.
MCQ 14. Which of the following correctly represents a part of the continuous water cycle?
- A. Condensation → Evaporation → Precipitation
- B. Evaporation → Condensation → Precipitation
- C. Precipitation → Evaporation → Condensation
- D. Condensation → Precipitation → Evaporation
Answer: B. Evaporation → Condensation → Precipitation — The water cycle typically begins with water evaporating, forming water vapour, which then condenses to form clouds, and finally falls back to Earth as precipitation.
MCQ 15. Why do people often keep drinking water in an earthen pot (matka) to keep it cool during summer?
- A. The pot reflects sunlight very effectively.
- B. Water evaporates from the tiny pores, taking heat away from the pot.
- C. The pot adds cooling minerals to the water.
- D. Earthen pots are naturally cold regardless of the outside temperature.
Answer: B. Water evaporates from the tiny pores, taking heat away from the pot. — Earthen pots have tiny pores through which water slowly seeps out and evaporates. This evaporation process absorbs heat from the remaining water inside the pot, thus cooling it down.
MCQ 16. Which of the following is the solid state of water?
- A. Water
- B. Steam
- C. Ice
- D. Vapour
Answer: C. Ice — Ice is the solid form of water, which forms when liquid water cools down and freezes.
MCQ 17. What do we call the process when ice changes into water?
- A. Freezing
- B. Melting
- C. Evaporation
- D. Condensation
Answer: B. Melting — Melting is the process by which a solid, like ice, turns into a liquid, like water, usually due to an increase in temperature.
MCQ 18. Clouds are formed primarily due to which process in the water cycle?
- A. Evaporation
- B. Precipitation
- C. Condensation
- D. Transpiration
Answer: C. Condensation — Clouds are formed when water vapour in the atmosphere cools down and condenses into tiny liquid water droplets or ice crystals.
MCQ 19. Which state of water takes the shape of its container but maintains a fixed volume?
- A. Solid
- B. Liquid
- C. Gas
- D. Plasma
Answer: B. Liquid — Liquids have a definite volume but take the shape of the container they are in, unlike solids which have a fixed shape, or gases which fill the entire container.
MCQ 20. On a hot sunny day, water from a puddle disappears. This phenomenon is called:
- A. Boiling
- B. Freezing
- C. Evaporation
- D. Condensation
Answer: C. Evaporation — Evaporation is the process where liquid water turns into water vapour and rises into the atmosphere, which is why puddles dry up.
How to Use These Solutions
Attempt each question yourself first and only then compare with the worked answer. Marks in the CBSE board exam are awarded for the METHOD as much as the final result, so reproduce the steps rather than memorising the last line. Where a solution states a law, a formula or a definition, learn that wording — examiners look for it.
Related practice for this chapter: chapter MCQs, previous-year questions, revision notes and sample papers.