ORAL QUESTIONS
1. About three-fourths of the earth's surface is covered with water. Why then is there a shortage of water?
2. Does digestion of food need the presence of water?
3. Name the states of water: Solid _
Liquid _
Gas _
4. To convert one state of water into another, which physical quantity has to be changed?
5. There is moist air in a closed container. How can you reduce the quantity of water in the air?
6. Evaporation occurs at all temperatures. Then why do we hang our clothes to dry in the sun?
Answers
Answer:
1. 3/4 th of the earth's surface is covered with water there is still scarcity of water across the globe. this is because: Around 97% of total water is in oceans which is salty and not fit for human consumption. Out of reamining 3% fresh water, only 1% is available to us in form of rivers, lakes and streams.
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2. In fact, drinking water during or after a meal actually aids digestion. Water is essential for good health. Water and other liquids help break down food so that your body can absorb the nutrients. Water also softens stool, which helps prevent constipation.
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3. Solid, Liquid, Gas
4. In order to convert water from one physical state to another, the physical quantity that should be changed is temperature.
5. Dehumidifiers are used to reduce the moisture in the air in a closed container. Normally silica gel is used for this purpose. Some amount of silica gel if you put in the container, it will absorb moisture and the air is free from water vapour.
6. Evaporation takes place at all temperature. But we spread our wet clothes in sun to dry because evaporation takes place faster at high temperatures so that the clothes can dry faster. Even if there is a decrease in humidity then the process of evaporation takes faster.