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Class 6 Science: A Journey through States of Water, 8 practice questions with answers

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These are 8 practice questions on the eighth chapter of the new NCERT Class 6 Science textbook, Curiosity, called A Journey through States of Water. Each has a short answer and the textbook page it comes from. They cover naming changes of state, what makes water evaporate faster, how solids, liquids and gases behave, a wet khus curtain, humidity and moving air, how rain forms, why fresh water is scarce, and fogged spectacles. For heat and temperature, see our Class 6 Temperature and its Measurement guide. Try each question before you read the answer.

These questions are our own, drafted with AI help. Every fact was checked against the page it cites by a test script, but no practising teacher has reviewed them yet. If you find a mistake, please tell us.

What the chapter says you need

Facts from the NCERT textbook (Curiosity, Grade 6, Chapter 8, printed pages 143 to 162):

States and changes

Question 1. Name the change of state in each case: (a) a bathroom mirror fogs up during a hot shower; (b) a kulfi softens and drips in the sun; (c) a wet footprint on a hot terrace fades away; (d) melted chocolate sets hard in the fridge.

Answer: (a) condensation; (b) melting; (c) evaporation; (d) freezing. (a) Water vapour in the warm, damp air touches the cold mirror and turns into tiny droplets: condensation. (b) A solid turning into a liquid is melting. (c) The water turns into vapour and goes into the air: evaporation. (d) A liquid turning into a solid when it is cooled is freezing; the chapter shows that other substances, not only water, change state on heating or cooling. (Evaporation, page 145; condensation, page 148; melting and freezing, page 152.)

Question 2. After washing, a family dries rice in two ways: a thin layer spread on a mat in the sun on a breezy day, and a heap in a bowl in the shade. Which dries faster? Give three reasons from the chapter.

Answer: the thin layer in the sun on a breezy day. Water evaporates faster when (1) more of it is exposed to the air, as in a thin spread-out layer; (2) it is in sunlight rather than shade; and (3) the air around it is moving. The heap in the shade has a small exposed surface, no sun and still air, so it dries much more slowly. (Exposed area, page 154; sun, shade and wind, page 155.)

Question 3. (a) Sort these by the chapter's rules for solids, liquids and gases: a steel spoon, honey, a bar of soap, the air pumped into a football. Which keep their own shape, which take the shape of their container, and which spread out to fill all the space they are given? (b) All the air from the football is let out into a large, empty plastic bag, which is then tied shut. Does the air keep the football's round shape? What does it do instead?

Answer: (a) own shape: the spoon and the soap; shape of the container: honey; fills the whole space: the air in the football; (b) no; it spreads out through the whole bag and takes the bag's shape. (a) A solid, like the steel spoon or the bar of soap, keeps its own shape whatever it is put in. A liquid, like honey, has no fixed shape: it flows (slowly, for honey) and takes the shape of its container, while its volume stays the same. A gas, like the air pumped into the football, has no fixed shape and spreads out into the whole space it is given, filling the ball right up to its skin. (b) A gas has no fixed shape of its own. The football's round shape belonged to the ball, not to the air. Let into the bag, the same air spreads out into all the space inside it and takes the bag's shape instead. (Solids, liquids and gases, page 151.)

Evaporation in daily life

Question 4. On hot, dry summer days, some families hang a curtain of khus grass in a window and keep sprinkling it with water. Air blowing in through the wet curtain makes the room feel cooler. (a) Using the chapter, explain why. (b) Why must the curtain be kept wet?

Answer: (a) the water in the curtain evaporates, and evaporation causes cooling; (b) once the water has evaporated, there is nothing left to evaporate. (a) As the air moves through the wet khus, water from it evaporates into the air, and the chapter's rule is that evaporation causes a cooling effect, so the air coming through the curtain is cooler. The moving air helps the water evaporate faster. (b) The cooling lasts only while there is water to evaporate. When the curtain dries out, the cooling stops, so it has to be wetted again and again. (Cooling effect, page 156; air movement, page 155; summary, page 160.)

Question 5. (a) A weather report says, "Humidity is very high today." What does this mean? (b) After a bath, one child dries her hair with a dryer blowing cool air; another child leaves his wet hair alone in a closed, steamy bathroom. Whose hair dries faster? Name the two conditions that make the difference.

Answer: (a) the air is holding a lot of water vapour; (b) the hair under the dryer; moving air and lower humidity. (a) How much water vapour the air is holding is called humidity, so high humidity means there is a lot of it. (b) Water evaporates faster when the air is moving, and more slowly when the air already holds a lot of water (high humidity). The dryer blows moving air over the hair; the steamy bathroom has still air that is already full of water vapour, so the water in the hair evaporates much more slowly there. The dryer's air is cool, so the difference here comes from the moving air, not from heat. (Humidity, pages 149 and 156; air movement, page 155.)

Water in nature

Question 6. Put these in the order in which they happen when rain forms: (a) drops become heavy and fall; (b) the vapour cools high up and condenses around dust into tiny droplets that make clouds; (c) water evaporates from the ground, lakes and the sea; (d) many tiny droplets join into bigger drops.

Answer: (c), (b), (d), (a). Water from the Earth's surface evaporates into the air. Higher up, the air is cooler, and the vapour condenses, usually around dust particles, into tiny droplets that float as clouds. Many droplets join into bigger drops, and drops that become heavy enough fall as rain (or, in special conditions, as hail or snow). (Clouds and rain, pages 157 and 158; evaporation from the Earth's surface, page 159.)

Question 7. Most of the Earth's water is in the oceans. Why, then, do many parts of the world face a shortage of water?

Answer: only a small part of Earth's water can be used, and demand keeps growing. Most of the Earth's water lies in the oceans, which we cannot use directly; only a little of it is water that plants, animals and people can actually use. As the population grows, more people need water, and this rising demand causes shortages in many places. That is why the chapter asks us to use water wisely, avoid wasting it, and keep water bodies free from pollution. (Water cycle and water use, page 159.)

Question 8. (a) A child wearing spectacles steps out of a cool, air-conditioned car into warm, humid monsoon air, and the lenses suddenly fog up with tiny drops. Which change of state has happened, and why on the lenses? (b) A room looks completely dry. Is there any water vapour in its air? How do you know, if you cannot see it?

Answer: (a) condensation, because the lenses are colder than the air; (b) yes, there is. (a) The lenses were cooled in the car. When the water vapour in the warm, humid air outside comes in contact with their cold surface, it turns into tiny water droplets: condensation. (b) Water vapour is invisible, but the chapter says it is always mixed into the air, even at ordinary room temperature, and that water evaporating from drying clothes and mopped floors keeps adding to it. Looking dry does not mean the air holds no vapour. (Condensation, page 148; water vapour in the air, page 151.)

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Sources

All opened and read on 2 November 2026. Page numbers are the printed page numbers of the textbook; printed page = PDF page + 142 for this chapter.

The facts are from the textbook pages above. The questions, answers and checks are our own. This guide is general information; follow your teacher and the textbook.

Practise with the worksheet: States of Water, Class 6 worksheet. Printable, in English, Hindi and Marathi, with an answer key.