Monday, 28 December 2020

Chapter 14 Water


 Chapter 14 – water

ACTIVITY-1: To estimate the quantity of water used. (Page No.- 144, 145)


Question 1- Does every person use same quantity of water every day?

Answer- No.


ACTIVITY- 2: Inter-conversion of three states of water. (Page No.- 146)


Question 1- What happens to ice-cream when it is taken out of the refrigerator?

Answer- Ice-cream melts and converts into liquid form.

Question 2- What is the state of ice-cream?

Answer- Solid.


ACTIVITY- 3: Evaporation of water in clothes. (Page No.- 147)


Question 1- What happens when you spill water on the floor in hot summer days?

Answer- Water evaporates in the air.


Question 2- Why cow dung cakes are kept in sunlight?

Answer- To evaporate the water content in cow dung cakes, so that they dry up.


ACTIVITY- 4: To understand condensation of water. (Page No.- 148)


Question 1- Why do we observe water droplets outside water bottle when taken out from a refrigerator?

Answer- Due to condensation of atmospheric water vapours on touching cool water bottle.




Question 1- Fill In The Blanks.

a). The process of changing of water into its vapour is called evaporation.

b). The process of changing water vapour into water is called condensation.

c). No rainfall for a year or more may be lead to drought in that region.

d). Excessive rains may cause flood.

e). Three states of water are solid, liquid and gas.

f). In plants, transpiration takes place through stomata.


Question 2- Write True Or False.

a). Ice on cooling changes to steam. (False)

b). Evaporation of water takes place in sunlight. (True)

c). We should not repair the pipe having leakage. (False)

d). Water in ocean is fit for drinking. (False)

e). Drip irrigation method is useful for farming. (True)


Question 3- Match The Column:-


1. Water conservation             a. Solid form of water (2)

2. Snow                                   b. Sunny day (4)

3. Precipitation                        c. Rainwater harvesting (1)

4. Evaporation                         d. Ground water (5)

5. Fresh water                          e. Rain from clouds (3)


Question 4. Choose The Correct Answer.


(i). How much part of earth is covered with water?

a) Two third ()

b) Half

c) One third

d) Three fourth


(ii). Fog appearing on a cold winter morning is the result of:

a) Condensation ()

 b) Evaporation

c) Precipitation

d) None


(iii). Which of the source of water is not used for drinking:

a) River

b) Ocean ()

c) Dam

d) Lake


(iv). Process of conversion of gas to liquid is called:

a) Evaporation

b) Melting

c) Condensation ()

d) Boiling

(v). About how much percentage of water is present in human body:

a) 60%

b) 70% ()

c) 80%

d) 90%


Question 5- Very Short Answer Type Questions.


(i) What are the main sources of water?

Answer- Rain, rivers and ground water.


(ii) What is the advantage of drip irrigation?

Answer- With drip irrigation water is saved.


(iii) What is the effect of temperature on evaporation?

Answer- Rate of evaporation increases with rise in temperature.


(iv) Differentiate between ground water and surface water.

Answer- Surface water exists in lakes, rivers and other water bodies. But ground water exists under the surface of earth.


(v) What is transpiration?

Answer- Transpiration is the process of releasing excess water by plants into air.

Question 6- Short Answer Type Questions.


(i) Explain floods and its effects.

Answer- An overflow of large amount of water due to heavy rain is known as flood.

Effects of floods- (1). Many people and animals die during floods.

(2). Water supply and electricity are disrupted.

(3). Wide spread of communicable diseases.

(4). Roads, bridges, houses and automobiles are destroyed.


(ii) Define condensation. Give two examples?

Answer- The process of changing vapours into liquid form is called condensation. Examples: Formation of clouds and fog appearing on a cold winter morning.


(iii) Explain formation of clouds.

Answer- When the air moves up, it gets cooler and cooler. After reaching sufficient heights, the air becomes so cool that the water vapours present in it condenses to form tiny drops of water called droplets which remain floating in air and thus clouds are formed.

(iv) Write three ways to conserve water.

Answer- (1) Use drip irrigation method.

(2). Rain water harvesting.

(3). Stopping the leakage of water pipes and taps as soon as possible.


(v) What is drought and what are its effects?

Answer- Very low rainfall over a prolonged period is called drought.

Effects of drought- (1). It leads to the death of many animals.

(2). Plant life is affected.

(3). It leads to shortage of water and food.


Question 7- Long Answer Type Questions.


(i) Explain the uses of water.

Answer- (1). About 70% of human body consists of water.

(2). Water helps to control our body temperature.

(3). Water helps to excrete waste products from our body.

(4). Water is important for growth of plants.

(5). Water maintains the temperature of earth.

(6). Water is essential for our many daily life activities.


(ii) Explain water cycle with diagram.

Answer- Water cycle is a cyclic process in which water is circulated between the earth and the atmosphere. In the presence of sunlight, water from water bodies like ocean, lakes, rivers etc. evaporates. This process is known as evaporation. These water vapours make clouds at heights by condensation. From clouds water falls back to earth in form of rain and snow.


(iii) Why there is need to conserve water? Write techniques of rain water harvesting.

Answer- Fresh clean water is available in limited amount. With rising population, the demand of water is increasing day by day. So it is the need to conserve water and use it carefully.

Techniques of rain water harvesting- (1). Rain water is collected on the roof of the house or building. It is then stored in storage tanks. This water can be used as per requirement.

(2). Rainwater is allowed to go into the ground directly to recharge ground water.