Aavi is right. Ice and water are the same substance in two different states.

• Keep an ice cube in a cup: it melts into water, and nothing is added to it.
• Keep water in a freezer: it becomes ice. Nothing gets added in the freezer; only cooling happens.

The ice cube changes into water. So ice and water are two forms (states) of the same substance. They behave differently: water flows and splashes, ice does not.

• Some water soaks into the soil, and some changes into water vapour and goes into the air (evaporation).
• Other examples: wet clothes drying, a wet floor drying after mopping, water drying on washed utensils, sweat drying, wet hair drying.
• Reason: water changes into invisible water vapour and mixes with the air.

No. There is no soil, and steel does not soak up water. Water does not seep through the steel either. The water evaporates into the air as water vapour.

• The underside of the plate stays dry the whole time, even though the water slowly disappears.
• So water does not seep through a steel plate. To be extra sure, we can keep the plate on dry paper and check that the paper stays dry.
• The water changed into water vapour (gaseous state) and went into the air.

The water on the hot pan quickly changes into steam. Steam is water vapour, part of which turns into tiny water droplets, so we can see it. Labels: hot pan, water drops, steam.

Drying of wet clothes, drying of a mopped floor, sweat drying on our body, drying of wet hair, water drying on a road after rain, drying of papad and grains in the sun.

(iii) Both. Some water seeps into the ground and some evaporates into the air.

It evaporates very quickly into the air. That is also why your hands feel cool.

Possible reasons: ice came out and melted; water seeped through the glass; water vapour in the air turned into drops on the cold glass.

Correct reason: the water level inside does not go down, so nothing seeps out. Water vapour in the air touches the cold glass and condenses into droplets.

• Other places: outside a cold bottle from the fridge, on a bathroom mirror, on window glass on a cold morning, on the lid of a cooking pot.
• Dew in the morning: leaves and grass become cool at night and early morning, so water vapour in the air condenses on them as dew.
• Steel plate over boiling water: water vapour (steam) from the boiling water touches the cooler plate and condenses into drops.

• The mass on the balance increases slowly.
• Reason: water vapour from the air condenses on the cold outer surface and adds water to the glass.
• This alone does not prove that water is not seeping through.
• Modification: mark the water level with a marker or tape. The level does not go down, but extra water collects outside. So water is not seeping out; the extra water comes from condensation.

• Solids: stone, wood, glass, iron nail, sugar, eraser.
• Liquids: honey, kerosene, petrol, fruit juice, vinegar.
• Gases: oxygen, carbon dioxide, nitrogen, cooking gas (LPG), water vapour.

The smell spreads through the air in all directions, like a gas, and reaches our nose.

• Ice → water: heat it, for example keep it in the sun or near a warm place.
• Water → ice: cool it in a freezer.
• Solid → liquid on heating: candle wax, butter, ghee, chocolate, coconut oil.
• Liquid → solid on cooling: melted wax, ghee, coconut oil (in winter).

A. Solid · B. Liquid · C. Gas · 1. Melts · 2. Evaporates · 3. Freezes · 4. Condenses

• Evaporation is faster on a hot day and slower on a cold day.
• It is faster when there is wind or a fan, and when water is spread out (like a spread-out cloth).
• It is slower on a rainy (humid) day.

• Kept the same: amount of water, place and time of keeping.
• Changed: exposed area of water. Measured: time taken to dry completely.
• Conclusion: water on the plate (larger exposed area) dries faster than water in the cap.
• Milk: the water in the milk evaporates, again faster from the plate, but a thin dry layer of milk solids is left behind.

Example: Does moving air make water evaporate faster?

• Kept the same: amount of water, same type of plate, same room.
• Changed: one plate under a running fan, one plate away from the fan.
• Result: the plate under the fan dries faster.

• Water in sunlight evaporates faster than water in shade.
• Clothes dry faster on a windy day, because moving air increases evaporation.
• Clothes dry slowly on a rainy day because the air is humid.
• To dry faster on a rainy day: spread the clothes out well, hang them under a fan or in an airy place, and squeeze out extra water first.

• Water seeps through the tiny pores of the earthen pot and evaporates from its outer surface. Evaporation takes away heat, so the water inside becomes cool.
• Other examples: sprinkling water on the floor or roof in summer, sweat drying under a fan, a wet cloth on the forehead.
• Sanitiser makes our hands feel cool, because it evaporates quickly.

• Water in the wet sand evaporates through the outer pot and takes away heat, so the inner pot stays cool.
• Vegetables and fruits stay fresh for several days (often about a week) if the sand is kept wet.
• Conditions: how hot and dry the air is, wind, humidity, whether the sand is kept wet, and where the cooler is kept (shade and airy place work best).
• Instead of sand: wet sawdust, wet jute or cloth, or charcoal pieces.

Sample lines you can add (write your own too!):

The sun warms the sea, the vapour flies high,
It cools into clouds that float in the sky.

• Without burnt paper, there is little or no change above the water.
• With burnt paper, haziness (a cloud) appears above the water.
• Tiny smoke and dust particles help water vapour condense into droplets. Clouds in the sky form the same way.

(iv) The conversion of water vapour into its liquid state.

• (i) (b) water colours: the painting dries only when the water evaporates.
• (ii) (b) ink pen: the wet ink dries by evaporation.

• Natural grass contains water. Water keeps evaporating from its leaves and the moist soil, and evaporation causes a cooling effect.
• Plastic grass has no water to evaporate. It only heats up in the sun, so the space around it feels warmer.

Petrol, kerosene, perfume, hand sanitiser, spirit (alcohol), nail polish remover.

• A fan does not make the air cold. It only moves the air.
• Moving air carries away the water vapour near the wet clothes, so more water can evaporate quickly.
• The heat needed comes from the clothes and the surrounding air. That is why we feel cool under a fan when sweat evaporates.
• So a fan helps clothes dry faster.

• In 3–4 days, much of the water in the sludge evaporates.
• The sludge becomes lighter, so it costs less to transport.
• Dry sludge does not drip or spill, so it is easier and safer for workers to handle.

• Activities: drying clothes, mopping the floor, drying washed utensils, drying hair, cooling tea in a saucer, drying papad, chillies and grains in the sun, keeping water in a matka.
• How it helps: we spread clothes out in the sun and wind so they dry faster, keep water cool in earthen pots, and dry food grains so they do not spoil.

As ice and snow: snow on mountain tops (for example, the Himalayas), glaciers, ice at the North and South Poles, hailstones, and frost on cold mornings.

• Everyone needs water, so it is our right. But only a small part of Earth’s water is usable, and the need keeps growing.
• So it is our duty first to save water: close taps, fix leaks, reuse water for plants, and collect rainwater.
• We must also keep water bodies clean and not throw waste into them.
• Only if we look after water today will everyone have water tomorrow.

• Sprinkle a little water on the seat or wipe it with a wet cloth. As the water evaporates, it takes away heat and cools the seat.
• Next time, park in the shade or cover the seat.