Q1. Fill in the blanks.
Water vapor gets added to air by evaporation
The circulation of water between ocean and
land is known as the water cycle.
covers more than two thirds of the earth’s surface.
In atmosphere water is present in huge
quantities as vapors and clouds.
Water present in ocean and sea is unfit
Water evaporates faster on hot summer day
compared to cloudy day. True
Excessive rain in an area leads to droughts. False
Water is a natural resource. True
About one thirds of the Earth is covered
with water. False
Heating is essential to convert water into
its vapor. True
Q3. Which is the purest form of natural water?
Q4. Name the process involved in the formation of clouds.
Clouds form by a process called condensation.
Q5. Why water disappears from wet clothes as they dry up?
Due to evaporation
Q6. What are the different forms of water exists on earth?
Water exists on earth in three different forms – ice, water and vapor.
Q7. How much water is lost through transpiration by wheat plants
that give us one kilogram of wheat?
Nearly 500 litres
Q8. Define water cycle.
The circulation of water between ocean and land is known as the water cycle.
Q9. How water enters the air?
Water vapor enters the air through the processes of evaporation and transpiration.
Q10. Where do water in rivers and lakes come from?
Rivers and lakes get water from rain and melting of snow on the mountains.
Q11. Define condensation.
The process by which water vapor in the air is converted into liquid is called
Q12. What do you understand by conservation of water?
Water conservation means careful, economical and wise use of water resources.
Q13. Why water spilled on a floor dries up after some time?
Due to evaporation, water changes into water vapor and hence water spilled on a
floor dries up after some time.
Q14. Define transpiration.
Transpiration is a process through which excess water comes out of leaves into
the atmosphere in the form of vapor.
Q15. What is evaporation?
Evaporation is the process in which water changes to gaseous state due to an
increase in temperature.
Q16. Why is water in seas and oceans saline?
The water in sea and ocean is saline because the water in the seas and oceans
has many salts dissolved in it.
Q17. Why we rarely notice water vapor from a bucket full of
We rarely notice water vapor from a bucket full of water because evaporation of
water is a slow process.
Q18. Why does a mist of tiny water droplets form when we breathe
out on a window in winter?
When our warm breath touches a cold window, it condenses and forms a mist of
tiny water droplets.