Unit - 12 Air

 Unit - 12

Air

summary

1. Air is a mixture of different gases. This is not a compound.

2. Air contains nitrogen, oxygen, carbon dioxide, inert gases, water vapor and

There are dust particles.

3. Wind is all around us.

4. Air has no color, smell and taste. But it weighs and takes up space.

5. Air flows from one place to another.

6. The oxygen in the air makes things burn. Object in an “oxygen free place”.

can't burn

7. Green plants use carbon dioxide in the air to make food and sow manure. s

This stage is known as RRP Kash Sram Shan.

3. Answer the following questions:

  (a) What are the gases in the air? In what percentage are they found? s

  (b) Write any four properties of air.

(c) Any four utility articles of air.

  (d) How can it be shown that air contains water vapor?

  (e) Any two utility articles of nitrogen gas.

  (f) Any two utility articles of carbon dioxide gas.

  (g) How does it smell like rust?

Answer 👉 

(a) The gases in the air are nitrogen, oxygen, argon, and carbon dioxide. Nitrogen is the most abundant gas, making up about 78% of the air. Oxygen is the second most abundant gas, making up about 21% of the air. Argon is the third most abundant gas, making up about 0.9% of the air. Carbon dioxide is the fourth most abundant gas, making up about 0.04% of the air.

(b) Four properties of air are:

• Air is a mixture of gases.
• Air is colorless.
• Air is odorless.
• Air is transparent.

(c) Four utility articles of air are:

• Air is used for breathing.
• Air is used for combustion.
• Air is used for cooling.
• Air is used for transportation.

(d) Air contains water vapor, which can be shown by the following experiment:

• Take a glass of cold water and place it in a warm room.
• After a few minutes, you will see that the outside of the glass is covered with water droplets.
• This is because the water vapor in the air has condensed on the cold surface of the glass.

(e) Two utility articles of nitrogen gas are:

• Nitrogen is used to make fertilizers.
• Nitrogen is used to make explosives.

(f) Two utility articles of carbon dioxide gas are:

• Carbon dioxide is used to make carbonated beverages.
• Carbon dioxide is used to make dry ice.

(g) Rust is a reddish-brown substance that forms on iron and steel when it is exposed to oxygen and water. Rust has a metallic, earthy smell.