Environmental Science MCQ – Asked in Previous Years, WBCS Mains

Answer – A. Stratosphere
Explanation-The stratosphere is the atmospheric layer that contains the highest concentration of O3 gas, commonly known as ozone. Ozone plays a crucial role in absorbing and filtering out a significant portion of the sun’s ultraviolet (UV) radiation.

Answer – D. Rocks
Explanation-The hydrosphere refers to all the water on Earth’s surface, including oceans, lakes, rivers, groundwater, and even water vapor in the atmosphere. Rocks are not considered part of the hydrosphere as they do not contain water.

Answer – C. Lithosphere
Explanation-The lithosphere refers to the rigid outermost layer of Earth’s crust, including the solid landmasses, rocks, and minerals. It is not part of the atmosphere. The atmosphere consists of different layers such as the troposphere, stratosphere, and ozonosphere.

Answer – C. Synthetic stone chips
Explanation-Fly ash, which is a byproduct of coal combustion, can be utilized in various ways to minimize waste and environmental impact. It is commonly used in the construction industry for making Portland fly ash cement (A), fly ash-based building bricks (B), and fillers in concrete (D). These applications help reduce the need for traditional cement, conserve natural resources, and decrease carbon emissions associated with concrete production. However, synthetic stone chips (C) are not a recommended use for fly ash. Fly ash does not possess the necessary properties to be effectively utilized as synthetic stone chips. Synthetic stone chips are typically made from other materials like polymers or natural stone aggregates. It’s important to note that the recommended uses of fly ash can vary depending on specific regulations, standards, and local conditions. Therefore, it is essential to consult relevant guidelines and local authorities to determine the appropriate and efficient utilization of fly ash in a specific region.

Answer – D. Transesterification
Explanation-Biodiesel is prepared through the chemical reaction known as transesterification. It involves converting vegetable oils or animal fats into fatty acid methyl esters (FAME), which are commonly referred to as biodiesel. This process involves reacting the fats or oils with an alcohol, such as methanol, in the presence of a catalyst.

Answer – C. Sewage
Explanation-Sewage is a biodegradable pollutant as it consists of organic matter that can be broken down and decomposed by natural processes. On the other hand, dye effluents, bleaching effluents, and heavy metals are non-biodegradable pollutants that pose environmental challenges.

Answer – D. Sedimentation
Explanation-The first step in sewage treatment is sedimentation. During this process, the wastewater is allowed to settle in a tank, allowing solid particles and heavier materials to sink to the bottom. This step helps in the removal of larger solid waste particles from the sewage.

Answer – B. PAN (Peroxyacetyl nitrate)
Explanation-Photochemical smog is primarily generated by the reaction of sunlight with pollutants such as nitrogen oxides (NOx) and volatile organic compounds (VOCs). Peroxyacetyl nitrate (PAN) is one of the key components formed in the atmosphere due to the photochemical reactions involving NOx and VOCs.

Answer –D. Recycling
Explanation-Recycling is an immediate remedial measure to tackle non-degradable plastic waste pollution. By recycling plastic waste, it can be transformed into new products, reducing the need for raw materials and minimizing environmental impacts.

Answer – D. Steel
Explanation-Radioactive wastes are harmful to humans and the environment. They emit radiation that can cause cancer and other health problems. It is important to store and dispose of radioactive wastes safely. Steel is a strong and durable material that can withstand the weight of radioactive wastes. It is also relatively inexpensive and easy to work with. Steel containers can be made leak-proof by welding the seams and using thick walls. Other materials that can be used for leak-proof containers for radioactive wastes include concrete, glass, and plastic. However, steel is the most commonly used material because it is the most cost-effective and offers the best protection from radiation. Dumping radioactive wastes into the sea is not a safe option. The wastes can leak out of the containers and contaminate the marine environment. This can harm marine life and pose a health risk to humans who eat seafood.