Water ( By - Dharmendra Sir)

 A. VERY SHORT ANSWER QUESTIONS: 

1. Name the process by which the underground water reservoirs

 are charged.

Ans. Rainwater harvesting

2. Which evaporates faster- hot water or cold water?

Ans. Hot water

3. Name the process by which plants lose water.

Ans. Transpiration

4. What kind of resource is water?

Ans. Renewable resource

5. In what form does the water present in the atmosphere return to the earth?

Ans. Rain, snow and hail.

B. SHORT-ANSWER QUESTIONS:

1. How does water from the earth’s surface escape into the atmosphere?

Ans. Water from the earth’s surface escapes into the atmosphere through evaporation, transpiration and respiration.

2. What happens if it does not rain for a long period?

Ans. If it does not rain for a long period, there will be drought- like conditions.

3.Draw a flowsheet chart describing the return of water to the oceans.

Ans.   

                                     

4. How are clouds formed?

Ans. Clouds are formed due to the condensation of water vapour in the air in the form of very small droplets of water. These floating droplets of water in the air appear as clouds.

5. What is meant by transpiration?

Ans. Loss of water from the leaves of the plants in the form of water vapour is called transpiration.

C. LONG ANSWER TYPE QUESTIONS: 

1. Why is natural water not considered safe for drinking?

Ans. Natural water is not considered safe for drinking because it is contaminated with many harmful chemicals such as arsenic and lead. It may also be contaminated with germs which cause water borne diseases like typhoid, jaundice dysentery etc. So it is necessary to treat the natural water before drinking.

2. Describe water cycle in nature.

Ans. Water escapes into the atmosphere from the oceans, seas, lakes, ponds and from wet bodies by evaporation. Plants release water into the air by transpiration. Animals and humans release water vapour into the atmosphere during breathing. Water vapour rises up in the atmosphere and gets condensed to form droplets and then return to earth as rain, snow and hail. This continuous circulation of water in nature is called water cycle.

3. What is the importance of water for humans, animals and plants?

Ans. a) Water regulates body temperature by the process of sweating and evaporation.

 b) Water inside the bodies of animals/human dissolves minerals, gases and many products of digestion and carries them at the place of need in the body.

c) Water provides a medium for all biochemical reactions inside our bodies to take place.

d) Water is essential for the germination of seeds, growth of plants and in photosynthesis.

4. What is meant by conservation of water? Suggest three methods to conserve water.

Ans. Careful, economical use and avoiding the wastage of water is called conservation of water.

Three methods to conserve water are as follows:

(1) Use only required quantity of water.

(2) Do not allow water to drip from defective taps.

(3) Trees and forests help rainfall. So to conserve water, we should plant more and more trees.

5. Describe rainwater harvesting.

Ans. Recharging the ground water reservoirs by allowing the collected rain water to percolate into the ground is called rainwater harvesting. 

Common techniques of rainwater harvesting are:

(1) Roof-top rainwater harvesting

(2) Open drain/tank water harvesting.

D. TICK THE ODD-ONE OUT GIVING REASON

1. Oceans, Rivers, Lakes, Polar regions, Springs

Ans. Polar regions because water present here in solid state and in rest other places it is in liquid state.

2. Dams, Hydroelectricity, Irrigation, Evaporation

Ans. Evaporation because rest others are related to the dams.

3. Rain, Snowfall, Hailstorm, Transpiration

Ans. Transpiration because it is the process of water leaving the earth and rest others are the process of returning water to the earth.

4. Excessive rainfall, Water logging, Floods, Fall in water level

Ans. Fall in water level because it is related to the drought and rest others are related to the flood.

5. Conservation of water, Rainwater harvesting, Tree plantation, Loss of water by plants and animals

Ans. Loss of water by plants and animals because rest others are related to conservation of water.

E. DEFINE THE FOLLOWING TERMS

1.Water crisis: Nonavailability of water to fulfil our daily requirements is called water crisis. It is a situation where the available potable, unpolluted water within a region is less than that region’s demand.

2.Evaporation and Condensation: Conversion of any liquid into its vapour by heating is called evaporation and conversion of vapour a substance into its liquid form by cooling is called condensation.

3. Desalination: The process of removal of the dissolved salts from the sea/ocean water is called desalination.

4. Hydroelectricity: Hydroelectricity is producing electricity by the force of fast-moving water such as rivers or waterfalls.

HOTS: HIGHER ORDER THINKING SKILLS

1. A closed container contains moist air. How can the quality of water in the air be reduced?

Ans. The water present in the air of the closed container can be reduced by the process of condensation. Due to condensation water vapour changes into liquid.

2. Evaporation takes place at all temperatures. Then why do we spread our wet clothes to dry in the sun?

Ans. We spread our wet clothes to dry in the sun because the heat of the sun increases the rate of evaporation and wet clothes get dried easily.