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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
Mention the contribution of the following scientists :
- Antoine Lavoisier
- Robert Boyle
- Joseph Priestley
- Sir W. Ramsay
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 |
Tick (√) the correct alternative from the choice given for the following statement.
The substance which accelerates the speed of a reaction without itself undergoing any change is called
Give a brief account of the discovery of air and the scientists involved.
Describe a simple experiment with the help of a diagram to show that Air occupies space
Name the following.
Gases that are harmful to the ozone layer
______ soil has pH 7.
Fill in the blank:
A candle burns in a jar of oxygen, but gets extinguished in ______
Take a squeezable bottle. Make a hole on the lid and close the bottle tightly. Bring the bottle near your face and press the bottle. What do you feel?
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.
