Chemistry Miscellaneous Part-3

Total Questions: 36

21. Which gas contributes to global warming through its greenhouse effect? [68th B.P.S.C. (Pre) 2022]

Correct Answer: (d) More than one of the above
Solution:Carbon dioxide, nitrous oxide, and methane — all are greenhouse gases contributing to global warming.

22. The relative contributions of carbon dioxide (CO₂), nitrous oxide (N₂O), chlorofluorocarbons (CFCs), and methane (CH₄) towards global warming are: [R.A.S./R.T.S. (Pre) 2016]

Correct Answer: (d) CO₂ > CH₄ > N₂O > CFCs
Solution:The relative contribution of main greenhouse gases towards global warming is as follows:
(i) Water vapour - about 60%
(ii) Carbon dioxide (CO₂) - about 26%
(iii) Methane (CH₄) - about 4-9%
(iv) Ozone (O₃) - about 3-7%
(v) Nitrous oxide (N₂O) - about 1.5%
(vi) Chlorofluorocarbons (CFCs) and others - 0.1-0.4%

23. Harnessing of nuclear energy often causes: [U.P. R.O./A.R.O. (Mains) 2017]

Correct Answer: (c) Thermal Pollution
Solution:Thermal pollution is caused by the use of water as a coolant in power plants (thermal and nuclear), which is then released into the natural environment at a higher temperature, reducing oxygen supply and affecting ecosystems.

24. 'Green Muffler' is used against which type of pollution? [U.P. P.C.S. (Mains) 2017]

Correct Answer: (d) Noise
Solution:Green mufflers are barriers of trees planted near noisy areas to reduce noise pollution by filtering and obstructing it.

25. Magnetic particles, suspected to cause neurodegenerative problems, are generated as environmental pollutants from which of the following? [I.A.S. (Pre) 2021]

  1. Brakes of motor vehicles
  2. Engines of motor vehicles
  3. Microwave stoves within homes
  4. Power plants
  5. Telephone lines

Select the correct answer using the code given below:

Correct Answer: (b) 1, 2 and 4 only
Solution:Magnetite is an oxide formed by iron ions of valences 2+ and 3+. Biologically formed nanoparticles of the strongly magnetic mineral, magnetite, were first detected in the human brain over 25 years ago. These brain magnetites display compelling similarity with the magnetite nanospheres formed by combustion, which are ubiquitous and prolific in urban, airborne particulate matter (PM). Magnetite can have potentially large impacts on the brain due to its unique combination of redox activity, surface charge, and strongly magnetic behavior. Magnetite could be toxic to the brain, generating harmful reactive oxygen species that have been linked to Alzheimer’s disease. In addition to occupational settings (including, for example, exposure to printer toner powders), higher concentrations of magnetite pollution nanoparticles are likely to arise from open fires and vehicles (tailpipe and brake wear) and/or industrial (power plants) PM sources. There is no clear evidence of the generation of magnetic particles from microwave stoves within homes or from telephone lines. Hence, option (b) is the correct answer.

26. With reference to Eutrophication, which of the following statements is/are correct? [U.P.P.C.S. (Pre) 2020]

  1. It is a phenomenon of nutrient enrichment of a water body.
  2. It depletes dissolved oxygen of the water.

Select the correct answer using the code given below:

Correct Answer: (c) Both 1 and 2
Solution:Eutrophication is excessive richness of nutrients in a lake or other body of water, frequently due to run-off from the land, which causes a dense growth of plant life. This induces excessive growth of algae and depletes dissolved oxygen in the water. It is often caused by the discharge of nitrate or phosphate containing detergents, fertilizers, or sewages into aquatic system.

27. Eutrophication of a water body results from— [R.A.S/R.T.S. (Re. Exam) (Pre) 2013]

Correct Answer: (d) High amounts of nitrogenous nutrients and orthophosphates.
Solution:Eutrophication occurs due to the excessive discharge of nutrients, especially phosphorous (P) in the form of phosphate, and nitrogen (N) in the form of nitrate and silicate, leading to algal blooms.

28. Biological Oxygen Demand (BOD) is a standard criterion for— [I.A.S. (Pre) 2017]

Correct Answer: (c) Pollution assay in aquatic ecosystems
Solution:Biological Oxygen Demand (BOD) is used to measure pollution in aquatic ecosystems. Organic and inorganic waste utilizes soluble oxygen in water bodies to decompose, reducing the amount of dissolved oxygen in the water.

29. Physico-chemical characteristics of water in water sources undergo changes due to— [I.A.S. (Pre) 1996]

Correct Answer: (c) Effluents
Solution:Physico-chemical characteristics of water in sources undergo changes due to effluents, which are considered water pollution, including discharge from sewage treatment or wastewater from industries.

30. In the context of which one of the following are the terms ‘pyrolysis and plasma gasification’ mentioned? [I.A.S. (Pre) 2019]

Correct Answer: (d) Waste-to-energy technologies
Solution:Pyrolysis and plasma gasification are high-temperature processes used for waste-to-energy technologies, safely disposing of organic waste and minimizing harmful by-products.