Water Chapter 14 Science Class 6 NCERT Solution
1. Fill up the blanks in the following:
(a) The process of changing of water into its vapour is called ________ .
(b) The process of changing water vapour into water is called _________ .
(c) No rainfall for a year or more may lead to __________ in that region.
(d) Excessive rains may cause ________ .
Answer:
(a) evaporation
(b) condensation
(c) drought
(d) 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.
(b) Steam rising from wet clothes while they are ironed.
(c) Fog appearing on a cold winter morning.
(d) Blackboard dries up after wiping it.
(e) Steam rising from a hot girdle when water is sprinkled on it.
Answer:
(a) condensation
(b) evaporation
(c) condensation
(d) evaporation
(e) evaporation
3. Which of the following statements are "true" ?
(a) Water vapour is present in air only during the monsoon. ( )
(b) Water evaporates into air from oceans, rivers and lakes but not from the soil. ( )
(c) The process of water changing into its vapour, is called evaporation. ( )
(d) The evaporation of water takes place only in sunlight. ( )
(e) Water vapour condenses to form tiny droplets of water in the upper layers of air where it is cooler ( )
Answer:
(a) False
(b) False
(c) True
(d) False
(e) True
4. Suppose you want to dry your school uniform quickly. Would spreading it near an anghiti or heater help ? If yes, how ?
Answer:
Spreading it near heater or anghiti will help, because due to more heat around; evaporation will be faster.
5. Take out a cooled bottle of water from refrigerator and keep it on a table. After some time you notice a droplets of water around it. Why ?
Answer:
The cold surface of cooled bottle cools the air around it, and the water vapour of the air condenses on the surface of the bottle.
6. To clean their spectacles, people often breath out on glasses to make them wet. Explain why the glasses become wet.
Answer:
The moist air coming out from mouth condenses on glasses to make glasses wet.
7. How are clouds formed?
Answer:
The process of condensation plays an important role in formation of cloud. As water vapour goes higher from the surrface of earth, it gets cooler. At sufficients heights the air becomes so cool that the water vapour present in it condenses to form tiny drops of water called droplets. It is these tiny droplets that remain floating in air and appear to us as clouds.
8. When does a drought occur ?
Answer:
If it does not rain for one or two years, the soil continues to lose water by evaporation and transpiration. Since it is not being brought back by rain, the soil becomes dry. The level of water in ponds and wells of the region goes down and some of them may even dry up. The ground water may also become scarce. This may lead to drought.