Water

Q1. Fill in the blanks.

                          i.        Water vapor gets added to air by evaporation and transpiration.

                         ii.        The circulation of water between ocean and land is known as the water cycle.

                        iii.        Water covers more than two thirds of the earth’s surface.

                        iv.        In atmosphere water is present in huge quantities as vapors and clouds.

                        v.        Water present in ocean and sea is unfit for drinking.

Q2. True/False

                         i.        Water evaporates faster on hot summer day compared to cloudy day. True

                        ii.        Excessive rain in an area leads to droughts. False

                       iii.        Water is a natural resource. True

                       iv.        About one thirds of the Earth is covered with water. False

                        v.        Heating is essential to convert water into its vapor. True

Q3. Which is the purest form of natural water?

Ans. Rain water

Q4. Name the process involved in the formation of clouds.

Ans. Clouds form by a process called condensation.

Q5. Why water disappears from wet clothes as they dry up?

Ans. Due to evaporation

Q6. What are the different forms of water exists on earth?

Ans. 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?

Ans. Nearly 500 litres

Q8. Define water cycle.

Ans. The circulation of water between ocean and land is known as the water cycle.

Q9. How water enters the air?

Ans. Water vapor enters the air through the processes of evaporation and transpiration.

Q10. Where do water in rivers and lakes come from?

Ans. Rivers and lakes get water from rain and melting of snow on the mountains.

Q11. Define condensation.

Ans. The process by which water vapor in the air is converted into liquid is called condensation.

Q12. What do you understand by conservation of water?

Ans. Water conservation means careful, economical and wise use of water resources.

 
Q13. Why water spilled on a floor dries up after some time?

Ans. Due to evaporation, water changes into water vapor and hence water spilled on a floor dries up after some time.

Q14. Define transpiration.

Ans. Transpiration is a process through which excess water comes out of leaves into the atmosphere in the form of vapor.

Q15. What is evaporation?

Ans. 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?

Ans. 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 water?

Ans. 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?

Ans. When our warm breath touches a cold window, it condenses and forms a mist of tiny water droplets.