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प्रश्न
Explain the following observations very briefly
A firki does not rotate in a closed area.
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उत्तर
A firki rotates due to the air movement present in the surrounding and a closed area doesn’t support air movement. Hence, a firki will rotate only when placed in an open area due to the presence of moving air all around.
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संबंधित प्रश्न
Match the statements in Column A, with those in Column B.
| Column A | Column B |
| 1. Largest Constituent of air, which dilutes the activity of oxygen. | (a) Oxygen |
| 2. A gas used for filling weather observeation balloons. | (b) Carbonic acid |
| 3. An acid formed by the dissolution of sulphur dioxide gas in water. | (c) Sulphuric acid |
| 4. An acid formed by the dissolution of carbon dioxide in water. | (d) Helium |
| 5. A gas vital for respiration. | (e) Nitrogen |
Write ‘True’ or ‘False’ in front of following statement.
Atmospheric nitrogen is directly absorbed by the plants to form plant proteins.
How is greenhouse effect produced?
Discuss harmful effects of greenhouse effect.
Give two uses of the following component present in air:
carbon dioxide
Name two air pollutants which cause acid rain.
Explain Lavoisier’s experiment which provided evidence to the discovery of components in air.
Mention two advantages of wind energy.
The process of conversion of iron into hydrated form of oxides is called _______.
Paheli kept some water in a beaker for heating. She observed that tiny bubbles appeared before the water started to boil. She boiled the water for about 5 minutes and filled it in a bottle up to the brim and kept the bottle air tight till it cooled down to room temperature.
Do you think tiny bubbles will appear on heating the water taken out from the bottle? Justify your answer.
