Question 1.
Fill in the blanks in the following :
(a) The process of changing water into its vapour is called ______.
Answer:
Evaporation
(b) The process of changing water vapour into water is called ______.
Answer:
Condensation
(c) No rainfall for a year or more may lead to ______ in that region.
Answer:
Drought
(d) Excessive rains may cause ______.
Answer:
Floods
Question 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 qn 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
Question 3.
Which of the following statements are “True”?
(a) Water vapour is present in the air only during the monsoon.
Answer:
False
(b) Water evaporates into the air from oceans, rivers, and lakes but not from the soil.
Answer:
False
(c) The process of water changing into its vapour, is called evaporation.
Answer:
True
(d) The evaporation of water takes place only in sunlight.
Answer:
False
(e) Water vapour condenses to form tiny droplets of water in the upper layers of air where it is cooled.
Answer:
True.
Question 4.
Suppose you want to dry your school uniform quickly. Would spread it near an anghiti or heater help? If yes, how?
Answer :
Yes. Spreading uniform near anghiti or heater will help in drying because near anghiti or heater, the temperature is much higher and hence the process of evaporation of water is faster. This will lead to quick drying of the uniform.
Question 5.
Take out a cooled bottle of water from the refrigerator and keep it on a table. After some time you notice a puddle of water around it. Why?
Answer :
The air around the cooled bottle of water gets cooled and water vapour present in it condenses into the water which collects as a puddle of water around the bottle.
Question 6.
To clean their spectacles, people often breathe out on glasses to make them wet. Explain why the glasses become wet.
Answer :
When we breathe out, water vapour also comes out with exhaled air. This water vapour when comes in contact with the glasses of spectacles makes them wet.
Question 7.
How are clouds formed?
Answer :
When the air containing water vapour moves up, it gets cooler and cooler. At sufficient 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 the air and form clouds.
Question 8.
When does a drought occur?
Answer :
Drought occurs when it does not rain for a long period.