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Nature's Treasures - Air

Grade 6CBSE

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

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Air is a mixture of several gases. The major components are Nitrogen (N2N_2) which makes up approximately 78%78\% and Oxygen (O2O_2) which is about 21%21\%.

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The remaining 1%1\% consists of Carbon Dioxide (CO2CO_2), Argon, other noble gases, water vapor, and dust particles.

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The envelope of air that surrounds the earth is known as the Atmosphere. It extends several kilometers above the Earth's surface.

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Oxygen is essential for the survival of all living organisms as it is required for respiration and is also necessary for the process of burning (combustion).

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Plants use Carbon Dioxide (CO2CO_2) from the air to prepare their food through the process of photosynthesis, releasing Oxygen (O2O_2) back into the atmosphere.

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Air is matter because it occupies space and has mass. It also exerts pressure in all directions.

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The balance of Oxygen and Carbon Dioxide in the atmosphere is maintained through the cycle of respiration in animals and photosynthesis in plants.

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Wind is moving air. It helps in the dispersal of seeds and pollen, movement of sailing yachts, and generates electricity through windmills.

📐Formulae

Composition of Air≈78% Nitrogen+21% Oxygen+1% Other gases\text{Composition of Air} \approx 78\% \text{ Nitrogen} + 21\% \text{ Oxygen} + 1\% \text{ Other gases}

Photosynthesis: 6CO2+6H2O→Sunlight/ChlorophyllC6H12O6+6O2\text{Photosynthesis: } 6CO_2 + 6H_2O \xrightarrow{\text{Sunlight/Chlorophyll}} C_6H_{12}O_6 + 6O_2

Respiration: C6H12O6+6O2→6CO2+6H2O+Energy\text{Respiration: } C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{Energy}

💡Examples

Problem 1:

If a sample of air in a sealed container has a total volume of 500 mL500 \text{ mL}, calculate the approximate volume of Oxygen present in it.

Solution:

Volume of Oxygen=21% of 500 mL\text{Volume of Oxygen} = 21\% \text{ of } 500 \text{ mL} Volume=21100×500=105 mL\text{Volume} = \frac{21}{100} \times 500 = 105 \text{ mL}

Explanation:

Since oxygen constitutes approximately 21%21\% of the air by volume, we multiply the total volume by 0.210.21.

Problem 2:

A student weighed an empty football and found it to be 400 grams400 \text{ grams}. After pumping air into it, the weight increased to 412 grams412 \text{ grams}. Calculate the mass of the air pumped inside.

Solution:

412−40012\begin{array}{r} 412 \\ - 400 \\ \hline 12 \end{array} Mass of air=12 grams\text{Mass of air} = 12 \text{ grams}

Explanation:

To find the mass of the air, we subtract the mass of the empty football from the mass of the inflated football.

Problem 3:

Why do mountaineers carry oxygen cylinders with them while climbing high mountains?

Solution:

As we go higher into the atmosphere, the air becomes thinner and the amount of available Oxygen (O2O_2) decreases.

Explanation:

The density of air decreases with altitude, leading to a drop in atmospheric pressure and oxygen levels, making breathing difficult at high altitudes.