Long Questions: Air Around Us | NCERT Summary: UPSC PDF Download

Q1: What is the importance of air in our lives?
Ans: We use air in various day to day activities such as:

• Air contains oxygen, which we need to breathe.
• Plants consume carbon dioxide in the air during photosynthesis.
• Air produces a protective atmosphere over the globe, which helps to keep the temperature stable.
• Air is required for the movement of ships, yachts, and planes.
• Birds need air to fly.
• Air is required for pollination of seeds.
• Windmills are used to generate electricity.

Q2: Explain the concept of air and its properties. Describe the composition of air and the role of oxygen, nitrogen, carbon dioxide, and other gases.
Ans: Air is the mixture of gases that surrounds the Earth. It has properties like mass, weight, and occupies space. The main components of air are nitrogen (78%) and oxygen (21%), with trace amounts of carbon dioxide, argon, and other gases.

Composition of Air:

• Nitrogen: Makes up the majority of air and is essential for life.
• Oxygen: Necessary for respiration and combustion.
• Carbon Dioxide: Supports plant growth through photosynthesis.

These gases work together to support life and various natural processes.

Q3: Describe the process of respiration and its importance. Explain how oxygen and carbon dioxide are exchanged in the respiratory system. Provide examples to illustrate the role of respiration.
Ans: Respiration is the process by which living organisms take in oxygen and release carbon dioxide to produce energy. Oxygen is inhaled into the lungs, where it diffuses into the bloodstream and is carried to cells. Carbon dioxide, a waste product, is carried back to the lungs and exhaled.
Importance of Respiration:

• Provides energy for body functions.
• Releases carbon dioxide, maintaining its level in the body.

Example: When you run or exercise, your body requires more energy, so you breathe faster to take in more oxygen for respiration.

Q4: Explain the concept of the atmosphere and its layers. Describe the role of the troposphere, stratosphere, mesosphere, and thermosphere.
Ans: The atmosphere is the layer of gases that surrounds the Earth. It is divided into several layers based on temperature changes.
Layers of the Atmosphere:

• Troposphere: Closest to Earth's surface, where weather occurs.
• Stratosphere: Contains the ozone layer that absorbs harmful UV radiation.
• Mesosphere: Protects Earth from meteoroids; coldest layer.
• Thermosphere: Contains ionized gases and absorbs high-energy radiation.

Each layer plays a vital role in maintaining Earth's conditions.

Q5: Describe the concept of air pressure and its variation with altitude. Explain how air pressure is measured using a barometer. Provide examples to illustrate the effects of air pressure.
Ans: Air Pressure is the force exerted by the weight of air on a surface. It decreases with increasing altitude because there are fewer air molecules higher up.

• Measuring Air Pressure: A barometer is used to measure air pressure. A mercury barometer consists of a glass tube filled with mercury inverted in a mercury container. The height of the mercury column in the tube indicates air pressure.
• Effects of Air Pressure: Low air pressure is associated with bad weather, while high air pressure indicates fair weather. Air pressure also affects weather patterns and can be felt during changes in altitude.

Q6: Explain the concept of wind and its causes. Describe how air moves from areas of high pressure to areas of low pressure. Provide examples of global winds and local winds.
Ans: Wind is the movement of air caused by differences in air pressure. Air flows from areas of high pressure to areas of low pressure due to pressure differences.

• Global Winds: Earth's rotation and unequal heating create global wind patterns. Examples include the trade winds, westerlies, and polar easterlies.
• Local Winds: Local temperature differences lead to local winds like sea breezes (day) and land breezes (night).

Example: A sea breeze occurs when cool air from the sea replaces warm air over the land during the day.

Q7: Describe the concept of air pollution and its sources. Explain how human activities contribute to air pollution and its impacts on health and the environment. Provide examples of pollutants and their effects.
Ans: Air Pollution is the presence of harmful substances in the air that affect human health and the environment.
Sources of Air Pollution:

• Vehicular Emissions: Cars and trucks release pollutants from exhaust.
• Industrial Emissions: Factories release chemicals and particles.
• Burning of Fossil Fuels: Power plants and households burn coal, oil, and gas.
• Agricultural Activities: Pesticides and fertilizers contribute pollutants.

Effects: Air pollution leads to respiratory diseases, allergies, and global warming. Pollutants like sulfur dioxide can cause acid rain, harming plants and aquatic life.

Q8: Explain the concept of rain and the water cycle. Describe how water evaporates, forms clouds, and precipitates as rain. Provide examples to illustrate the water cycle.
Ans: Rain is the process of water falling from clouds to the ground.
Water Cycle:

• Evaporation: Sun heats water, turning it into water vapor.
• Condensation: Water vapor cools, forming clouds.
• Precipitation: Clouds become heavy and release water as rain, snow, sleet, or hail.

Example: Water from a pond evaporates, forms clouds, and then falls as rain over a forest, completing the water cycle.

Q9: Describe the concept of weather and climate. Differentiate between the two and explain their significance. Provide examples to illustrate the difference between weather and climate.
Ans: Weather is the condition of the atmosphere at a specific time and place, including temperature, humidity, wind, and precipitation. Climate is the average weather conditions of a region over a longer period.
Significance:

• Weather: Affects daily activities and immediate plans.
• Climate: Influences long-term patterns and ecosystem behavior.

Example: On a summer day, the weather might be hot and sunny, but the climate of a region might be characterized as tropical due to consistent warm temperatures.

Q10: Explain the concept of ozone and its importance. Describe the role of the ozone layer in protecting life on Earth. Provide examples of human activities that lead to ozone depletion and its consequences.
Ans: Ozone is a molecule made up of three oxygen atoms. The ozone layer is a region in the stratosphere that absorbs harmful UV radiation from the Sun.
Importance of Ozone:

• Shields Earth from harmful UV radiation.
• Prevents skin cancer, cataracts, and other health issues.
• Ozone Depletion: Human-made chemicals like chlorofluorocarbons (CFCs) destroy ozone molecules. Ozone depletion increases UV radiation, harming human health and ecosystems.

Example: The use of aerosol sprays containing CFCs contributes to ozone layer depletion, resulting in increased UV exposure and environmental damage.