Pollution - UPSC MCQ

Explanation: Microbeads are manufactured solid plastic particles of less than one millimeter in their largest dimension. They are most frequently made of polyethylene but can be of other petrochemical plastics such as polypropylene and polystyrene. These tiny pieces of plastic are added to rinse-off products such as face scrubs, toothpastes and shower gels. The small spherical beads, designed to help with exfoliation and then be washed down the drain, often slip through waste-water treatment plants and end up in the seas. They do not degrade over time and can transport toxic chemicals into marine organisms. Microbeads can have a damaging effect on marine life, the environment and human health. This is due to their composition, ability to adsorb toxins and potential to transfer it up the marine food chain.
Option (b): There is no evidence of microbeads causing skin cancer in children. This is a made up statement, hence incorrect.
Option (c): Again this is a made up statement as there is no evidence of plants being able to absorb microbeads.
Option (d): This too is a made up statement. Microbeads are not used in food adulterants.
Educational Objective: To know about Microbeaads impact on environment.

Explanation: If we observe the options carefully, we can see that plutonium is mentioned in three of the given four options. But, Plutonium is a radioactive substance and it is highly unlikely that it is an ingredient in making electronic goods. If we were to eliminate this option we will arrive at the answer easily.
Heptachlor is an organochlorine compound that was used as an insecticide. And hence does not contribute to e-waste. Lead is used in glass panels and gaskets in computer monitors.
Cadmium occurs in SMD chip resistors, infrared detectors, and semiconductor chips. Beryllium is commonly found on motherboards and finger clips. Chromium VI (Hexavalent Chromium) is used as a corrosion protector of untreated and galvanized steel plates and as a decorative or hardener for steel housings Plastics. Mercury is used in thermostats, sensors, relays, switches, medical equipment, lamps, mobile phones and batteries.
Educational Objective: To know about E wastes related pollution.

Explanation: Normally rain water has a pH of 5.6 due to the presence of H+ ions formed by the reaction of rain water with carbon dioxide present in the atmosphere. When the pH of the rain water drops below 5.6, it is called acid rain. Acid rain is a by product of a variety of human activities that emit the oxides of sulphur and nitrogen in the atmosphere. Burning of fossil fuels (which contain sulphur and nitrogenous matter) such as coal and oil in power stations and furnaces or petrol and diesel in motor engines produce sulphur dioxide and nitrogen oxides. SO₂ and NO₂ after oxidation and reaction with water are major contributors to acid rain, because polluted air usually contains particulate matter that catalyzes the oxidation.
2SO₂ (g) + O₂ (g) + 2H₂O (l) → 2H₂SO₄ (aq)
4NO₂ (g) + O₂ (g)+ 2H₂O (l) → 4HNO₃ (aq)
Educational Objective: To know about Acidrain impact on environment.

Explanation: Formation of photochemical smog. When fossil fuels are burnt, a variety of pollutants are emitted into the earth’s troposphere. Two of the pollutants that are emitted are hydrocarbons (unburnt fuels) and nitric oxide (NO). When these pollutants build up to sufficiently high levels, a chain reaction occurs from their interaction with sunlight in which NO is converted into nitrogen dioxide (NO₂). This NO₂ in turn absorbs energy from sunlight and breaks up into nitric oxide and free oxygen atom.
NO₂(g) NO(g) + → O(g)
Oxygen atoms are very reactive and combine with the O₂ in air to produce ozone.
O(g) + O₂ (g) → O₃ (g)
The ozone formed in the above reaction (ii) reacts rapidly with the NO(g) formed in the reaction (i) to regenerate NO₂. NO₂ is a brown gas and at sufficiently high levels can contribute to haze.
NO(g) + O₃ (g) → NO₂ (g) + O₂ (g)
Ozone is a toxic gas and both NO₂ and O₃ are strong oxidizing agents and can react with the unburnt hydrocarbons in the polluted air to produce chemicals such as formaldehyde, acrolein and peroxyacetyl nitrate (PAN).

Educational Objective: To know about basicconcepts related to photo chemical smog. 

Explanation: In steel furnace, coke reacts with iron ore, releasing iron and generating CO and CO2 gases. Due to use of coal, pollutants such as SOx and NOx are released, thus all are correct options.
Educational Objective: To know about pollution caused by industrial sector.

Explanation: Normally, oxygen would bind to hemoglobin in the lungs and be released in areas with low oxygen partial pressure (e.g. active muscles). When carbon monoxide binds to hemoglobin, it cannot be released as easily as oxygen. The slow release rate of carbon monoxide causes an accumulation of CO-bound hemoglobin molecules as exposure to carbon monoxide continues. Because of this, fewer hemoglobin particles are available to bind and deliver oxygen, thus causing the gradual suffocation associated with carbon monoxide poisoning.
Educational Objective: To know about Various impact of Carbon Dioxide.

Explanation: Contaminants are anything physical, chemical, biological, or matter in water. Drinking water may reasonably be expected to contain at least small amounts of some contaminants. Some drinking water contaminants may be harmful if consumed at certain levels in drinking water while others may be harmless. The presence of contaminants does not necessarily indicate that the water poses a health risk.
The following are general categories of drinking water contaminants and examples of each:

• Physical contaminants primarily impact the physical appearance or other physical properties of water. Examples of physical contaminants are sediment or organic material suspended in the water of lakes, rivers and streams from soil erosion.
• Chemical contaminants are elements or compounds. These contaminants may be naturally occurring or man-made. Examples of chemical contaminants include nitrogen, bleach, arsenic, salts (flouride), pesticides, metals, toxins produced by bacteria, and human or animal drugs.
• Biological contaminants are organisms in water. They are also referred to as microbes or microbiological contaminants. Examples of biological or microbial contaminants include bacteria, viruses, protozoan, and parasites.
• Radiological contaminants are chemical elements with an unbalanced number of protons and neutrons resulting in unstable atoms that can emit ionizing radiation. Examples of radiological contaminants include cesium, plutonium and uranium.

Educational Objective: To know aboutvarious pollutants contamination in drinking water 

Explanation: Flame retardants are used to make it more difficult for a material to ignite or to reduce the spread of fire, but they do not make the material non-flammable.
Polybrominateddiphenyl ethers (PBDEs) are used as flame retardants They’re persistent, bio-accumulative, and toxic to both humans and the environment.
Educational Objective: To know about Brominated Flame Retardants.

Explanation: Statement 1 and 3 are correct. Fly ash can be used in the production of bricks for building construction and as a replacement for some of the Portland cement contents of concrete.Fly ash is made up of aluminium silicate, silicon dioxide, calcium oxide. Fly ash particles are oxide rich and consist of silica, almina, oxides of iron, calcium and magnesium and toxic heavy metals like lead, arsenic, cobalt and copper. Statement 3 is false as it says Fly ash is made up of only two components namely: silicon dioxide and calcium oxide.
Educational Objective: To know about fly ash and its impact on environment.

Explanation: Bioremediation is a process used to treat contaminated media, including water, soil and subsurface material, by altering environmental conditions to stimulate growth of microorganisms and degrade the target pollutants. Statement 1 is correct.

• Toxic metals like Cadmium and Lead cannot be treated with this technique. Hence statement 2 is correct.
• It is possible to create microorganisms with the approach of Genetic Engineering for bioremediation.

Educational Objective: To know about Bioremediation process to control pollution.

Explanation: Carbon Dioxide and Methane are green house gases which are released into the atmosphere because of natural processes as well. These gases are not air pollutants unlike Carbon Monoxide, Sulfur Dioxide and Nitrogen Dioxide which pollute the air. Hence Carbon Dioxide and Methane are not part of Air Quality Index.
Educational Objective: To know aboutAir Quality Index.

Explanation: Biochemical oxygen demand (BOD) represents the amount of oxygen consumed by bacteria and other microorganisms while they decompose organic matter under aerobic (oxygen is present) conditions at a specified temperature. Even though the amount of dissolved oxygen in water is small, up to about ten molecules of oxygen per million of water, it is a crucial component of natural water bodies; the presence of a sufficient concentration of dissolved oxygen is critical to maintaining the aquatic life and aesthetic quality of streams and lakes. Hence C is the answer.
Educational Objective: To know about Biological Oxygen Demand.

Explanation: Open biomass burning, which refers to burning of forests, savanna/grasslands and crop residue, releases large amounts of trace gases such as Nitrogen Oxides (NOx), CO, methane (CH₄), non-methane hydrocarbon (NMHCs), carbon dioxide (CO₂) and particulate matter.
Educational Objective: To know about biomass burning and its impact on environment.

Explanation: Agricultural soils contributed to over 70% of N₂O emissions from India in 2010, followed by waste water (12%) and residential and commercial activities (6%). Since 2002, N₂O has replaced methane as the second largest Greenhouse Gas (GHG) from Indian agriculture. Statement 1 is correct.

• Cattle account for 80% of the ammonia production. Statement 2 is correct.
• The poultry industry recorded an excretion of reactive nitrogen compounds of 0.415 tonnes in 2016. That is anticipated to increase to 1.089 tonnes by 2030. Statement 3 is correct.

Educational Objective: To know about agriculture sector contribution to pollution.