Test: Air and Atmosphere - Class 6 MCQ

Shining a light beam in a dark room reveals dust particles suspended in the air. This experiment helps visualize the presence of air pollutants and emphasizes the need for clean air for health and visibility.

Nitrogen constitutes about 78% of the Earth's atmosphere. It is essential for various biological processes but does not support combustion. Understanding the composition of air is crucial for studying environmental science and biology.

Oxygen is crucial for combustion, as it reacts with fuels to produce heat and light. This chemical reaction is fundamental in various applications, from cooking to powering engines. Without oxygen, fires cannot sustain themselves.

When water vapor cools, it condenses into tiny droplets, which can form clouds or dew. This process is essential for the water cycle and helps maintain ecological balance by distributing water in various forms.

Inverting a glass tumbler in water shows that air occupies space. The water level inside the tumbler is lower because the air trapped inside prevents the water from rising fully. This experiment illustrates the presence of air around us.

Photosynthesis by plants plays a crucial role in balancing oxygen and carbon dioxide levels. By taking in carbon dioxide and releasing oxygen, plants help maintain the atmospheric composition necessary for life on Earth.

Nitrogen is not a greenhouse gas and does not contribute to the greenhouse effect. In contrast, gases like carbon dioxide, methane, and water vapor trap heat in the atmosphere, leading to global warming.

Elevated carbon dioxide levels contribute to global warming by enhancing the greenhouse effect, which traps heat in the atmosphere. This phenomenon leads to climate change, affecting weather patterns and ecosystems worldwide.

The primary purpose of respiration is to produce energy by breaking down glucose in the presence of oxygen. This energy is essential for all biological processes, allowing organisms to grow, move, and function.

Leguminous plants, such as peas and beans, have symbiotic relationships with bacteria that enable them to convert atmospheric nitrogen into compounds that are beneficial for their growth. This process enriches the soil and supports agricultural practices.

Acid rain, which results from pollutants like nitrogen and sulfur oxides mixing with water vapor, can severely damage buildings, forests, and aquatic ecosystems. This environmental issue highlights the need for reducing emissions to protect our surroundings.

The ozone layer serves to absorb harmful ultraviolet (UV) rays from the sun, protecting living organisms from potential damage. Thinning of the ozone layer due to pollutants can lead to increased skin cancer and other health issues.

Smog reduces visibility by creating a thick haze in the air, which can lead to dangerous driving conditions and health issues. Understanding smog formation and its effects is crucial for urban planning and public health initiatives.

Carbon dioxide is utilized by plants during photosynthesis to produce food. In this process, plants convert carbon dioxide and water into glucose and oxygen, providing energy for growth and releasing oxygen into the atmosphere.

Air pressure decreases with altitude because the density of air molecules decreases as you go higher. This is why we often experience difficulty breathing at high altitudes, where there is less oxygen available.

Oxygen makes up approximately 21% of the atmosphere. This gas is vital for respiration in animals and plants and plays a key role in combustion processes.

Carbon dioxide is a byproduct of respiration, which occurs in both plants and animals. During this process, oxygen is consumed to break down food, releasing energy and carbon dioxide back into the atmosphere, contributing to the gas balance.

Planting more trees significantly reduces air pollution by absorbing carbon dioxide and releasing oxygen. This natural process is vital for maintaining a healthy atmosphere and combating climate change.

Air pollution mainly occurs through the burning of fossil fuels like coal, oil, and gas, which releases harmful gases and particulates into the air. This pollution adversely affects health and the environment, highlighting the need for cleaner energy sources.

Carbon dioxide is used in fire extinguishers because it does not support combustion. When released, it displaces oxygen, effectively suffocating the fire, which is essential for safety in firefighting.