Page 171 - Science Class 06

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i About 71% of the earth’s surface is covered with water.
i Water is used for various purposes.
i About 97% of the hydrosphere is contained in the world’s oceans.
i About 0.01% of hydrosphere is fit for consumption and agriculture.

i Air and water are essential for all living beings.
i Air is the mixture of gases.
i The atmosphere which envelopes the earth is also made of air.

i Nitrogen is the largest constituent of air.
i Respiration is completed in two parts— breathing and release of energy.

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Exercise
A. Tick ( ) the correct op on. 3
1. How much of the total amount of water is fit for drinking?
(a) 2 percent (b) 5 percent

(c) 7.4 percent (d) 0.01 percent
2. Which one of the following is not an effect of drought?
(a) Acute shortage food (b) Collapse of buildings
(c) Cracks in the soil (d) Dying of crops

3. Which of the following is not a cause of flood?
(a) Cyclone (b) Tsunami
(c) Heavy rainfall (d) Earthquake

4. __________ is the largest cons tuent of air.
(a) Oxygen (b) Carbon dioxide
(c) Nitrogen (d) Argon
5. Which of the following gases is filled in electric bulbs?

(a) Oxygen (b) Hydrogen
(c) Argon (d) Carbon dioxide
B. Fill in the blanks.

1. Water is essen al for the __________ of seeds and growth of plants.
2. About 2.16 percent of water is available as __________ .
3. Drought may occur in every type of __________ region.
4. Due to __________ humus of the soil is lost.
5. Aqua c animals take in air through their__________ .

C. Write True or False.
1. About 70 percent of our body weight is due to water.

Science-6 171