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Chhattisgarh Board Class 8 Science Chapter 3 Solution

Last updated on February 6th, 2024 at 12:53 am

CG Board Class 8 Science Air

 

Chhattisgarh Board Class 8 Science Chapter 3 Solution Textbook question and answers as well as extra question and answers from the chapter

 

Choose the correct alternative-

  1. Which gas has the highest percentage in air?

a) Oxygen b) Nitrogen c) Helium d) Carbon dioxide

 

2. Nitrogen is used in the storage of food items because

  1. it provides oxygen to the food items
  2. it provides carbon-dioxide to the food items
  3. it provides protein to the food items
  4. it keeps the food fresh.

 

3. Unit measure of atmospheric pressure is equal to the column of mercury pressure of –

a) 76 cm b) 76 mm c) 1.013 mm d) 10.13 mm

 

4. Oxygen gas as compared to water is –

a) heavier b) lighter c) equal d) none of these

 

5. The cause of heating up of our atmosphere is

a) Ozone layer b) greenhouse effect c) nitrogen d) oxygen

 

Fill in the blanks

  1. ………………………..gas helps in burning.[oxygen]
  2. Of a nitrogen rich fertilizer ………………………..is the main source.[ammonia]
  3. The atmospheric pressure ………………………..on going upwards from the earth surface.[decreases]
  4. Acid rain is due to ………………………..and ………………………..gases. [sulphur di-oxide and nitrogen oxide]
  5. Oxygen is ………………………..in water. [less soluble]

 

Find the correct sentences from these and rewrite the wrong sentences correctly.

  1. The percentage of oxygen in air is 10 percent.
  2. On heating potassium permanganate we get nitrogen gas.
  3. Sulphur dioxide when mixed with air, pollutes it.
  4. The air pressure in the balloon is due to the air filled in it, striking the walls of the balloon.
  5. Because of the inertness of nitrogen gas, it is filled in the electric bulbs.

 

Corrected sentences:

  1. The percentage of oxygen in air is 21 percent.
  2. On heating potassium permanganate we get oxygen gas.
  3. Sulphur dioxide, when mixed with air, pollutes it.
  4. The air pressure in the balloon is due to the air filled in it, exerting force on the walls of the balloon.
  5. Because of the inertness of nitrogen gas, it is filled in the electric bulbs to prevent oxidation of the filament.

 

Answer the following questions.

 

Q- What are the components of air?

The main components of air are approximately:

  • Nitrogen (N2): 78%
  • Oxygen (O2): 21%
  • Argon (Ar): 0.9%
  • Water vapor (H2O): 0.04%
  • Carbon dioxide (CO2): 0.03%
  • Other gases and dust particles.

 

Q- What are the causes of air pollution? What measures would you adopt to stop it?

Causes of air pollution and measures to stop it:

Causes:

  • Vehicle emissions (carbon monoxide, oxides of nitrogen)
  • Industrial activities (particulate matter, sulfur dioxide, nitrogen oxides)
  • Burning of fossil fuels
  • Agricultural practices (ammonia)

Measures:

  • Shift to cleaner energy sources
  • Improve vehicle emissions standards
  • Implement pollution control devices in industries
  • Promote afforestation
  • Reduce open burning of waste

 

Q- What are the main uses of nitrogen gas?

Main uses of nitrogen gas:

  • Essential for the growth of plants and animals.
  • Reacts with hydrogen to form ammonia, a key component in the production of fertilizers.
  • Inert nature makes it useful for preventing oxidation in electric lamps.
  • Used to create an inert atmosphere for storing certain food items, preventing spoilage.
  • Liquid nitrogen is used as a cooling agent in various industrial applications, including the storage of blood and organs for transplantation.

 

Q- What is acid rain? How is it harmful for us?

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