Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
The atmosphere is a thick blanket of air that surrounds the Earth and is held in place by gravity.
Air is a mixture of different gases, mainly Nitrogen (), Oxygen (), Carbon Dioxide (), and water vapor ().
Nitrogen () is the most abundant gas, making up about of the air. It is important for plant growth but cannot be taken directly from the air by most living things.
Oxygen () makes up about of the air. It is essential for the survival of all living organisms for breathing and is also required for burning (combustion).
Carbon Dioxide () and other gases like Argon make up the remaining . Plants use for the process of photosynthesis to prepare food.
Air has specific properties: it occupies space, has weight, and exerts pressure in all directions.
Water vapor () in the air is responsible for weather changes like rain, fog, and snow through the process of condensation.
Air pollution is the presence of harmful substances such as smoke, dust, and toxic gases in the atmosphere, which can harm living beings.
📐Formulae
💡Examples
Problem 1:
If a sample of air contains units of gas in total, how many units of Oxygen () would you expect to find based on standard composition?
Solution:
Approximately units.
Explanation:
Since Oxygen () makes up of air, we calculate of : units.
Problem 2:
Explain why a candle goes out when covered with a glass jar.
Solution:
The candle consumes the available Oxygen () and then stops burning.
Explanation:
Burning requires Oxygen (). Once the limited supply of inside the jar is used up, the chemical reaction of combustion cannot continue, and the flame is extinguished.
Problem 3:
Identify the gas responsible for the formation of dew on grass during a cold morning.
Solution:
Water vapor ().
Explanation:
Air contains water in the form of gas called water vapor (). When the temperature drops at night, this vapor cools down and turns into liquid water droplets through condensation.