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Water
Air, Water, and Weather Std IV
| Question | Answer |
|---|---|
| About ___________ of the earth is covered with water. | 71% |
| Where is water found on earth? | Rivers, seas, oceans, underground |
| The sun slowly changes the water on the surface of the earth to change it into ________________________. | water vapour |
| Evaporation | The of process of change of water into water vapour due to heating |
| Evaporation takes place at a faster rate when: | 1. There is a strong wind 2. The exposed surface of water is large 3. The temperature of the surroundings is high 4. The air is dry. |
| Water vapour goes up to the __________ and forms ____________. | atmosphere clouds |
| The clouds form on the earth as _________________. Water vapour also forms ____________________________. | rain. dew, frost, fog, snow |
| Condensation | When water vapour cools down, it changes into drops of water. This is called condensation. |
| Three forms of water | Ice, water, water vapour |
| In nature, we also see water in the form of _________________________. | Fog, dew, frost, hail, and snow |
| Fog | This occurs when thick clouds of tiny drops of water form just above land or water |
| Dew | When the water vapour in the air condenses and appears as droplets in the ground and other surfaces. It is called dew. We often see dewdrops early in the morning (after a cold night) in leaves, flowers and standing vehicles. |
| Frost | When it is very cold, the dew or surface water freezes into tiny white crystals. This is called frost. |
| Hail | When raindrops pass through a very cold region of the atmosphere, they freeze and become hail. |
| Snow | When water vapour is suddenly cooled, it freezes into tiny white snowflakes. |
| This occurs when thick clouds of tiny drops of water form just above land or water | Fog |
| When the water vapour in the air condenses and appears as droplets in the ground and other surfaces. | Dew |
| When it is very cold, the dew or surface water freezes into tiny white crystals. | Frost |
| When raindrops pass through a very cold region of the atmosphere, they freeze and become _________ | Hail |
| When water vapour is suddenly cooled, it freezes into tiny white snowflakes. | Snow |
| The water in wells and rivers is impure due to | a. Insoluble impurities which can be seen seen, b. Soluble impurities which cannot be seen seen, and c. Disease-causing germs |
| Insoluble impurities | impurities which can be seen seen |
| Soluble impurities | impurities which cannot be seen seen |
| Two methods of purification of water | Sedimentation and decantation Filtration |
| Sedimentation and decantation | To separate insoluble impurities, let the water stand for some time. The impurities that are heavier than water will settle at the bottom of the water leaving it clear. This is called Sedimentation. |
| Decantation | Now slowly pour out this clear water into another vessel. This is called decantation. |
| Filtration | Water on the surface of the earth gets filtered when it passes through layers of soil to become underground water. That is why this water is mostly safe and fit for drinking, |
| Is water that is purified through sedimentation and decantation and filtration always safe for drinking? | No water purified through sedimentation and decantation and filtration may still contain germs and may be unfit for consumption. |
| How should water be purified for to make it safe for drinking? | Chlorination Bleaching powder Potassium permagnate in wells Boiling water Water filter |
| Chlorination | Adding Chlorine to water. |
Created by:
Moi.A
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