1. Fill up the blanks in the following:
(a) The process of changing of water into its vapour is called Evaporation_______________.
(b) The process of changing water vapour into water is called ______Condensation__________.
(c) No rainfall for a year or more may lead to _______Drought__________ in that region.
(d) Excessive rains may cause _________flood________.
2. State for each of the following whether it is due to evaporation or condensation:
(a) Water drops appear on the outer surface of a glass containing cold water.
Answer:
- Condensation
(b) Steam rising from wet clothes while they are ironed.
Answer:
- Evaporation
(c) Fog appearing on a cold winter morning.
Answer:
- Condensation
(d) Blackboard dries up after wiping it.
Answer:
- Evaporation
(e) Steam rising from a hot girdle when water is sprinkled on it.
Answer:
- Evaporation
3. Which of the following statements are “true”?
(a) Water vapour is present in the air only during the monsoon. ( False )
(b) Water evaporates into the air from oceans, rivers and lakes but not from the soil. ( False )
(c) The process of water changing into its vapour, is called evaporation. ( True )
(d) The evaporation of water takes place only in sunlight. (False )
(e) Water vapour condenses to form tiny droplets of water in the upper layers of air where it is cooler. ( True )
4. Suppose you want to dry your school uniform quickly. Would spreading it near an anghiti or heater help? If yes, how?
Answer:
Yes, It will help to dry quickly as heater will speed up the evaporation process of moisture from the school uniform.
5. Take out a cooled bottle of water from the refrigerator and keep it on a table. After some time you notice droplets of water around it. Why?
Answer:
As we know that the condensation process happens in a cooler temperature, Atmospheric air moisture get converted to droplets of water when they touch the cooled surface of a bottle.
6. To clean their spectacles, people often breathe out on glasses to make them wet. Explain why the glasses become wet.
Answer:
Because breath out air contains warm moisture which condenses on the surface of spectacles that is why spectacles become wet.
7. How are clouds formed?
Answer:
As we know, temperature decreases with increasing height from the surface. When the water vapour reaches some height they cooled and cloud formed after condensation.
8. When does a drought occur?
Answer:
Drought occurs when there is no rainfall for a longer duration( one year or two years). In drought, water bodies dried up, soil become hard and dry, groundwater also dried up, overall scarcity of water leads to loss of plant and animal.
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