Prepare for your 10th-grade exams with solved exercises on Environmental Chemistry, based on the PTB curriculum. Focus on key concepts like pollution, environmental impact, and sustainable practices.
Short Answer Questions:
- Explain the phenomenon of decreasing temperature in the troposphere.
- In the troposphere, the temperature decreases with altitude because the ground absorbs heat from the sun and warms the air above it. As you go higher, the distance from the heat source (Earth’s surface) increases, leading to lower temperatures.
2. Differentiate between primary and secondary air pollutants.
- Primary air pollutants are emitted directly from sources such as vehicles, factories, or natural processes (e.g., carbon monoxide, sulfur dioxide).
- Secondary air pollutants form in the atmosphere through chemical reactions between primary pollutants and other components, like ozone and smog.
- State the major sources of CO and CO₂ emission.
- CO (Carbon Monoxide): Emitted from vehicle exhausts, industrial processes, and incomplete combustion of fossil fuels.
- CO₂ (Carbon Dioxide): Emitted from burning fossil fuels, deforestation, and respiration.
- CO₂ is responsible for heating up the atmosphere, how?
- CO₂ traps heat in the atmosphere by absorbing infrared radiation emitted from the Earth’s surface, contributing to the greenhouse effect, which warms the planet.
- CO is a hidden enemy, explain its action.
- Carbon monoxide (CO) is a colorless, odorless gas that can bind to hemoglobin in the blood, preventing the transport of oxygen and leading to poisoning or even death in high concentrations.
- What threats are to human health due to SO₂ gas as air pollutant?
- Sulfur dioxide (SO₂) can cause respiratory problems, irritation of the eyes, worsening of asthma, and may lead to lung diseases with prolonged exposure.
- Which air pollutant is produced on anaerobic decomposition of organic matter?
- Methane (CH₄) is produced during the anaerobic decomposition of organic matter in places like landfills and wetlands.
- How acid rain increases the acidity of soil?
- Acid rain contains sulfuric and nitric acids, which lower the pH of the soil, leading to increased acidity. This can harm plant growth and soil organisms.
- Point out two serious effects of ozone depletion.
- Increased UV radiation exposure, leading to skin cancer and eye cataracts.
- Damage to marine ecosystems, especially affecting phytoplankton in the oceans.
- How ozone layer forms in the stratosphere?
- The ozone layer forms when ultraviolet (UV) light splits oxygen molecules (O₂) into individual oxygen atoms (O), which then combine with other oxygen molecules to form ozone (O₃).
- Why are 75% of the atmospheric mass lies within the troposphere?
- The troposphere contains most of the atmosphere’s water vapor and aerosols, and gravity pulls the atmospheric gases closer to Earth’s surface, concentrating most of the mass within this layer.
- How ozone layer is being depleted by chlorofluorocarbons?
- Chlorofluorocarbons (CFCs) release chlorine atoms when they are broken down by UV light in the stratosphere. These chlorine atoms react with ozone, breaking it down into oxygen molecules, thereby depleting the ozone layer.
Long Answer Questions:
- Write down the significance of atmospheric gases.
- Atmospheric gases such as nitrogen, oxygen, carbon dioxide, and argon play critical roles in supporting life on Earth. Oxygen is essential for respiration, carbon dioxide for photosynthesis, and nitrogen is a key component of the nitrogen cycle. The atmosphere also helps in regulating Earth’s temperature by absorbing and emitting thermal radiation.
- Give the characteristics of the troposphere. Why temperature decreases upwards in this sphere?
- The troposphere is the lowest layer of the atmosphere, characterized by weather changes, cloud formation, and high concentrations of water vapor. The temperature decreases with altitude because the ground absorbs heat from the sun, and air is heated from the bottom up.
- What are the characteristics of the stratosphere? Why temperature increases upwards in this sphere?
- The stratosphere lies above the troposphere and contains the ozone layer, which absorbs UV radiation, leading to higher temperatures with increasing altitude. This absorption of UV light heats the upper part of the stratosphere.
- CO₂ is necessary for plants but why its increasing concentration is alarming for us?
- While CO₂ is essential for photosynthesis, excessive amounts contribute to global warming and climate change by enhancing the greenhouse effect, causing sea level rise and extreme weather events.
- Why is CO considered a health hazard?
- Carbon monoxide (CO) is toxic because it binds to hemoglobin in red blood cells more effectively than oxygen does, reducing the blood’s ability to carry oxygen to body tissues and organs, leading to hypoxia and potentially fatal outcomes.
- Define acid rain. How it forms and what are its effects?
- Acid rain is rain that has been made acidic due to the presence of sulfuric and nitric acids formed from sulfur dioxide (SO₂) and nitrogen oxides (NOx) in the atmosphere. It leads to damage to aquatic life, forest degradation, and erosion of buildings.
- Compounds of sulfur are air pollutants. Describe the sources of these compounds along with their effects.
- Sources: Burning fossil fuels, industrial processes, and volcanic eruptions.
- Effects: Respiratory problems, acid rain formation, and environmental damage.
- Where does ozone layer lie in atmosphere? How is it depleting and how can we prevent its depletion?
- The ozone layer is located in the stratosphere, around 10-30 km above Earth’s surface. It is being depleted by chlorofluorocarbons (CFCs) and other ozone-depleting substances.
- Prevention: Reducing the use of CFCs, promoting ozone-friendly products, and international agreements like the Montreal Protocol.
- Oxides of nitrogen cause air pollution. Describe the sources of these compounds.
- Sources: Vehicle emissions, industrial processes, power plants, and lightning.
- Effects: Formation of acid rain, photochemical smog, and respiratory issues in humans.
