Air

Samacheer Book Back Questions And Answers For Science Standard 6 Term 2 “Air“

I. Choose the correct answer:
1. _____ is the percentage of nitrogen in the air.
(a) 78%
(b) 21%
(c) 0.03%
(d) l%

2. Gas exchange takes place in plants using _____.
(a) Stomata
(b) Chlorophyll
(c) Leaves
(d) Flowers

3. The constituent of air that supports combustion is _____.
(a) Nitrogen
(b) carbon-di-oxide
(c) Oxygen
(d) water vapour

4. Nitrogen is used in the food packaging industry because it _____.
(a) provides colour to the food
(b) provides oxygen to the food
(c) adds proteins and minerals to the food
(d) keeps the food fresh

5. _____ and _____ are the two gases, which when taken together, make up about 99 percentage of air.
I. Nitrogen
II. carbon-di-oxide
III. Noble gases
IV. Oxygen
(a) I and II
(b) I and III
(c) II and IV
(d) I and IV

II. Fill in the blanks:
1. _____ is the active component of air.
2. The gas given out during photosynthesis is _____.
3. _____ gas is given to the patients having breathing problems.
4. _____ can be seen moving in a beam of sunlight in a dark room.
5. _____ gas turns lime water milky.

Answers:
1. Oxygen(O₂)
2. Oxygen(O₂)
3. Oxygen (O₂)
4. Tiny dust particles
5. Carbon dioxide (CO₂)

III. True or False. If False, give the correct statement:
1. Inhaled air contains a large amount of carbon-di-oxide
2. Planting trees help in decreasing global warming
3. The composition of air is always exactly the same
4. Whales come up to the water surface to breathe in oxygen
5. The balance of oxygen in the atmosphere is maintained through photosynthesis in animals and respiration in plants.

Answers:
1. False (Inhaled air contains a large amount of oxygen)
2. True
3. False (The composition of air varies place to place & season to season)
4. True
5. False (The balance of oxygen is maintained through Photosynthesis in plants & respiration in animals)

IV. Match the following:
1. Moving Air                      A. Photosynthesis
2. Layer in which we live     B. Troposphere
3. Stratosphere                    C. Wind
4. Oxygen                            D. Ozone layer
5. carbon-di-oxide               E. Combustion

Answers:
1. C
2. B
3. D
4. E
5. A

V. Arrange the following statements in correct sequence:
1. Plants manufacture food by a process called photosynthesis.
2. Plants require energy for their growth.
3. Plants take in oxygen and release carbon-di-oxide just as animals.
4. Plants take carbon-di-oxide from the atmosphere, use chlorophyll in the presence of sunlight and prepare food.
5. Such oxygen is available to animals and human beings for breathing.
6. During this process, oxygen is released by plants.

Answers:
1. Plants require energy for their growth.
2. Plants manufacture food by a process called photosynthesis.
3. During this process, oxygen is released by plants.
4. Plants take in oxygen and release carbon-di-oxide just as animals.
5. Such oxygen is available to animals and human beings for breathing.
6. Plants take carbon-di-oxide from the atmosphere, use chlorophyll in the presence of sunlight and prepare food.

VI. Analogy:
1. Photosynthesis: _____:: Respiration: Oxygen
2. 78% of air: Does not support combustion:: _____: Supports combustion

Answers:
1. CO₂
2. 21% of air

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