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.
EXERCISE
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.
