3
– Properties Of Natural Resources
Q.1. Fill in the blanks with the
appropriate term:
(Temperature, volume, mass, density,
humidity, acidic, weight, neutral, shape)
(1) The capacity of air to
hold moisture depends upon the ……………..of the air.
(2) Water does not have a............ but has definite .............
and............
(3) While freezing, the .........
of water is lowered.
(4) ............. soil has pH 7.
Ans. (1) humidity (2)
shape, density, mass (3) density (4) Neutral.
Q 2. State whether the following statements are true or false :
(1) Sandy soil has low capacity for holding water.
(2) Sea water is a bad conductor of electricity.
(3) The substance in which a solute dissolves is called a solvent.
(4) The pressure exerted by air is called atmospheric pressure.
Ans. (1) True. (2) False, (Sea water is good conductor of
electricity.) (3) True. (4) True.
Q 3. With whom should I pair up?
Ans. (1) Air-Scattering of light
(2) Water - Excretion
(3) Soil – Plasticity
Q 4. What will happen if ...
(1) The amount of water vapour in the
air increases.
Ans. When the amount of water vapour increases in the air, the
humidity rises. The air becomes humid
(2) Only one crop is grown repeatedly in the soil.
Ans. If same crop is grown again and again, its texture disturbs
and the fertility is lowered. The soil does not support the cultivation and the
crops will not give proper yield.
Q. 5. Explain the picture in your own words:
Ans. (1) In figure 'a'
water is seen in the crevice over a land surface. This water is in
liquid form
(2) In figure 'b' the same
water is converting into solid ice.
(3) As the temperature is
decreasing, the water is freezing.
(4) Since there is
formation of ice, that means the temperature is less than 4 °C.
(5) The water whose
temperature is less than 4 °C becomes less dence, but its volume
Increases
(6) The water starts expanding which is shown by arrows in figure
‘B’
(7) Due to anomalous expansion of water the crevice in figure ‘b’ now
looks bigger than
the crevice in Figure ‘a’
Q. 6. Write answers to the following questions in your own words:
(1) How is light scattered
by the air?
iha Ans. (1) Air Consists of a mixture of very fine particles of
some gases, dust, smoke moisture. (2) When the light falls on the minute
particles present in the air, these part spread the light in all the directions
(3) This is called scattering of the light.
(2) What is the importance of air in transmission of sound?
Ans. (1) Air is the medium for the transmission of the sound. (2)
We are able to peto the sound due to the air around us. (3) The sound waves
travel through the medium of and reach us. (4) In absence of sound we cannot
hear the sound. Hence air is most import for the transmission of the sound.
(3) Why should a glass bottle completely filled with water never
be kept in freezer?
Ans.(1) Due to anomalous expansion of water, it expands while
getting frozen. (2) W the temperature goes below 4 °C, the density of water
start decreasing and at the same ti the volume increases. (3) Temperature in
freezer is always less than 4 °C. This caue expansion of the water. Due to
expansion the bottle may burst. (4) Bottle is made up of glas The broken glass
pieces may cause harm. Therefore the glass bottles should not be kept freezer
after completely filling them.
(4) Explain the various properties of water.
Ans. Water has following properties :
(1) Fluidity : Water has the property of fluidity, due to which it
can flow. Water therefore used for transport and for generation of electricity.
(2) Coolant : It can cool the heated equipments.
(3) Universal solvent : Almost all the things dissolve in water
and hence it is called universal solvent.
(4) Ability to perform body functions : Water takes part in the
different biochemical reactions taking place in the body,
(5) Cleaning abilities: Water can clean almost everything. Thus is
used in our day-to-day life.
(5) Why is the density of seawater more
than that of rain water?
Ans. There are many dissolved salts in
the son water. Therefore the density of sea water more than the rain water.
(6) What is the importance of good soil
structure ?
Ans. (1) Good soil structure results in good fertility of soil.
(2) When soil is of good quality the roots get sufficient supply of oxygen. (3)
In such soil the water drainage is good. (4) The plants grow well in such soil.
(7) What are the various uses of soil?
Ans. (1) Plant conservation
: Soil helps plants to grow
(2) Water conservation : Soil has water holding capacity.
Therefore, water is available to us, throughout the year.
(3) Plasticity : Plasticity is the property due to which soil can
be given any required shape. Therefore, various articles are made from soil.
They are baked and made hard for longer use. e.g., storage earthen pots,
earthen lamps, idols, bricks, etc.
(8) What is the need and importance of soil testing from the point
of view of farmers?
Ans. (1) The farmers wants a good produce from his crops. (2) By
testing the soil he understands the constituents of soil in his farm (3)
Colour, texture and the proportion of organic matter in the soil is tested by
various testing procedures. (4) If there is any deficiency in the soil that in
also found out Measures to be taken to remove deficiency are also suggested.
(5)The pH and the electrical conductivity tests are particularly useful in
understanding the characteristics of soil.
Q 7 Why is it said that - (Give scientific resons):
1)
Air is a homogeneous mixture of various gases.
Ans. There are many constituent gases in the air. They are in the
form of mixture. The saprate existence of each gas is not felt. The individual
gases cannot be separated easily. therefore the air is said to be the
homogenous mixture.
2)
Water is a universal solvent.
Ans. Many substances easily dissolve in water. Therefore, water is
said to be the universal solvent.
3) There is no
alternative to water for cleaning purposes.
Ans. Many substances can dissolve in water. Therefore for bathing,
cleaning utensils and washing clothes water becomes very useful solvent. It is
cheap, easily available remedy for cleaning purpose. Therefore, it is said that
there is no alternative to water for cleaning.
