Olympiad Test Level 1: Environmental Issues- 1 - Class 7 MCQ

Greenhouse Effect:
The greenhouse effect is the exchange of outgoing and incoming radiations that keeps the Earth warm. It is an important natural process that helps to maintain the Earth's temperature at a level suitable for sustaining life. Here is a detailed explanation of the greenhouse effect:
1. Energy from the Sun:
- The Sun emits energy in the form of electromagnetic radiation, including visible light, ultraviolet (UV) radiation, and infrared (IR) radiation.
- This energy reaches the Earth's atmosphere and some of it is reflected back into space, while the rest is absorbed by the Earth's surface.
2. Greenhouse Gases:
- The Earth's surface absorbs the incoming solar radiation and heats up.
- The heated surface emits energy in the form of infrared radiation.
- Some of this infrared radiation escapes back into space, but a significant portion is absorbed by greenhouse gases present in the Earth's atmosphere.
3. Greenhouse Gases and Heat Trapping:
- Greenhouse gases, such as carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and water vapor, have the ability to absorb and re-emit infrared radiation.
- When the infrared radiation is absorbed by these greenhouse gases, it causes them to vibrate and become excited.
- As a result, the greenhouse gases re-emit the absorbed energy in all directions, including back towards the Earth's surface.
4. Warming Effect:
- The re-emitted infrared radiation from greenhouse gases acts like a blanket, trapping heat in the Earth's atmosphere.
- This trapped heat warms the Earth's surface and lower atmosphere, leading to an increase in temperature.
- Without the greenhouse effect, the Earth's average surface temperature would be much colder, making it unsuitable for life as we know it.
5. Human Activities and Enhanced Greenhouse Effect:
- Human activities, such as the burning of fossil fuels, deforestation, and industrial processes, have increased the concentration of greenhouse gases in the atmosphere.
- This enhanced greenhouse effect is leading to an imbalance in the Earth's energy budget, causing global warming and climate change.
In conclusion, the greenhouse effect is a natural process that is essential for maintaining the Earth's temperature within a suitable range for life. However, human activities have intensified this effect, resulting in global warming and its associated consequences. It is crucial to reduce greenhouse gas emissions and adopt sustainable practices to mitigate the impacts of climate change.

Global Environmental Issues
- The global environmental issues refer to the problems that affect the environment on a global scale. These issues have the potential to cause significant harm to ecosystems, biodiversity, human health, and the overall well-being of the planet. Some of the key global environmental issues include:
1. Greenhouse Effect and Global Warming:
- The greenhouse effect is the process by which certain gases in the Earth's atmosphere trap heat, leading to an increase in the Earth's temperature. This phenomenon, known as global warming, is primarily caused by the emission of greenhouse gases from human activities such as the burning of fossil fuels and deforestation.
2. Biodiversity Loss:
- Biodiversity refers to the variety of life on Earth, including plants, animals, and microorganisms. The loss of biodiversity is a significant global environmental issue, primarily caused by habitat destruction, pollution, overexploitation, and climate change. It has severe consequences for ecosystems, as well as for human societies that depend on biodiversity for food, medicine, and other resources.
3. Desertification:
- Desertification is the process by which fertile land becomes desert-like, typically due to deforestation, overgrazing, and unsustainable agricultural practices. It leads to the loss of productive land, increased soil erosion, and the displacement of local communities. Desertification is a global environmental issue that affects many regions around the world.
Conclusion:
- All of the above issues, including the greenhouse effect and global warming, biodiversity loss, and desertification, are on the list of global environmental issues. These issues require urgent attention and concerted global efforts to mitigate their impact and ensure a sustainable future for our planet.

Answer:
The gas that does not contribute to global warming is Acetylene. Here is a detailed explanation:
Methane:
- Methane is a potent greenhouse gas that contributes to global warming.
- It is released from various sources such as natural gas production, livestock farming, and landfills.
Carbon dioxide:
- Carbon dioxide is one of the primary greenhouse gases responsible for global warming.
- It is released through the burning of fossil fuels, deforestation, and other industrial processes.
Sulfur:
- Sulfur is not a greenhouse gas and does not contribute to global warming.
- However, sulfur dioxide (SO2) is released into the atmosphere from burning fossil fuels, which can lead to acid rain and other environmental issues.
Acetylene:
- Acetylene is not a greenhouse gas and does not contribute to global warming.
- It is a hydrocarbon gas used in welding and cutting processes.
In summary, while methane, carbon dioxide, and sulfur contribute to global warming, acetylene does not have this effect.

By taking these small steps, you can help preserve our Earth's natural beauty.

Global warming is causing major changes in the weather patterns of the world.
Some key points to consider are:
- Rising temperatures: Global warming is primarily caused by the increase in greenhouse gases in the atmosphere, which trap heat from the sun. This leads to a rise in average global temperatures, resulting in changes in weather patterns.
- Extreme weather events: As temperatures increase, the frequency and intensity of extreme weather events such as hurricanes, heatwaves, and droughts also increase. These events can have devastating impacts on communities, economies, and ecosystems.
- Changing precipitation patterns: Global warming affects the distribution and intensity of rainfall. Some regions may experience more frequent and intense rainfall, leading to flooding, while others may experience prolonged droughts. These changes can disrupt ecosystems, agriculture, and water supplies.
- Melting ice and rising sea levels: Global warming is causing the melting of glaciers and polar ice caps, leading to rising sea levels. This can result in coastal erosion, increased flooding, and the loss of habitats for many species.
- Shifts in ecosystems: The changing climate can disrupt ecosystems and impact the distribution and behavior of flora and fauna. Some species may struggle to adapt to new conditions, leading to shifts in their populations or even extinction.
In conclusion, global warming is causing significant changes in the weather patterns of the world. These changes have far-reaching consequences for both human and natural systems, and it is crucial to take action to mitigate the impacts of global warming and work towards a sustainable future.

The most potent greenhouse gas is water vapour, which causes about 36-70% of the greenhouse effect. Carbon dioxide (9-26%), methane (4-9%) and Ozone (3-7%) are other major greenhouse gases.

Strategies for Reduction of Greenhouse Gases

• Tree Plantation: Planting more trees helps in reducing greenhouse gases as trees absorb carbon dioxide and release oxygen through photosynthesis.


• Less Carbon Dioxide Emission: Reducing carbon dioxide emissions from various sources such as burning fossil fuels, industrial processes, and transportation can significantly reduce greenhouse gases in the atmosphere.


• Use of Renewable Energy: Transitioning to renewable energy sources like solar, wind, and hydropower can help reduce greenhouse gas emissions associated with fossil fuel combustion.


• Sustainable Use of Resources: Promoting sustainable practices in agriculture, forestry, and land use can help reduce greenhouse gas emissions by minimizing deforestation, preserving natural habitats, and adopting efficient resource management techniques.

By implementing these strategies, we can mitigate the impact of greenhouse gases on the environment and work towards a more sustainable future.

Ways to conserve natural resources:

• Preventing wastage: Conserving natural resources involves reducing wastage by using them efficiently and responsibly.


• Save water: Water is a precious natural resource, and conserving it is crucial. Implementing water-saving techniques and using water-efficient appliances can help in this regard.


• Afforestation: Planting trees is an effective way to conserve natural resources. Trees help in maintaining the ecological balance, preventing soil erosion, and providing clean air and water.


• Energy conservation: Conserving energy can help in reducing the consumption of fossil fuels and other non-renewable resources. This can be achieved through practices such as using energy-efficient appliances, turning off lights when not in use, and promoting renewable energy sources.


• Recycling: Recycling helps in reducing the demand for raw materials, thus conserving natural resources. It involves converting waste materials into new products, reducing the need for extraction and production of new resources.

Incorrect Option:

Deforestation: Deforestation is not a way to conserve natural resources; rather, it involves the removal or destruction of trees and forests. Deforestation leads to the loss of biodiversity, contributes to climate change, and negatively impacts ecosystems.

By promoting practices such as preventing wastage, saving water, afforestation, energy conservation, and recycling, we can effectively conserve natural resources and preserve them for future generations.

To determine the number of trees that can be saved by recycling one ton of paper, we need to consider the amount of paper that can be produced from a tree and the average weight of a tree.
1. Amount of paper from a tree:
- On average, a tree can produce approximately 8,333 sheets of paper.
- Each sheet of paper weighs around 0.05 pounds.
2. Weight of one ton of paper:
- One ton is equal to 2,000 pounds.
3. Calculating the number of trees:
- Divide the weight of one ton of paper (2,000 pounds) by the weight of each sheet of paper (0.05 pounds) to find the total number of sheets: 2,000 / 0.05 = 40,000 sheets.
- Divide the total number of sheets (40,000) by the number of sheets produced from one tree (8,333) to determine the number of trees: 40,000 / 8,333 ≈ 4.8 trees.
Therefore, recycling one ton of paper can save approximately 5 trees.
Answer: B:

Nine - Recycling one ton of paper can save approximately 5 trees.

Global Warming Potential (GWP)

The Global Warming Potential (GWP) is a measure used to compare the ability of different greenhouse gases to trap heat in the atmosphere over a specific time period, usually 100 years. It quantifies the potential impact of a greenhouse gas relative to carbon dioxide (CO2), which is often used as a reference gas with a GWP of 1.

Gases Used as Reference for GWP Calculation

• Carbon Dioxide (CO2): Carbon dioxide is commonly used as the reference gas for GWP calculations. It has a GWP of 1, which means that other greenhouse gases are compared to its warming potential over a 100-year period.

Other Greenhouse Gases

• Methane (CH4): Methane is a potent greenhouse gas with a higher GWP than carbon dioxide. It has a GWP of 28-36, depending on the time period considered.


• Ozone (O3): Ozone is not used as a reference gas for GWP calculations. However, it is a greenhouse gas that can contribute to global warming.


• Nitrogen Dioxide (NO2): Nitrogen dioxide is also not used as a reference gas for GWP calculations. It is primarily a pollutant and a precursor to the formation of ground-level ozone.

In summary, carbon dioxide (CO2) is the gas used as a reference to calculate the Global Warming Potential (GWP) of other greenhouse gases. It serves as a baseline for comparing the warming potential of different gases over a specific time period.