Free Man and His Environment MCQs with Answers

251. A global agreement in specific control strategies to reduce the release of ozone-depleting substances was adopted by the:

• A. Montreal Protocol
• B. Kyoto Protocol
• C. Vienna Convention
• D. Rio de Janeiro Conference

Explanation: The Montreal Protocol was signed in Montreal, Canada, by over 150 countries at a convention in 1987 to cut the use of CFCs (chlorofluoro­ carbons). The aim of the protocol was to protect the ozone layer in the stratosphere by decreasing and eventually eliminating the use of ozone-depleting substances like CFCs. It is regarded as one of the most successful international treaties in modern history.

252. Biochemical oxygen demand (BOD) in a river water:

• A. Has no relationship with concentration of oxygen in the water.
• B. Gives a measure of Salmonella in the water.
• C. Increases when sewage gets mixed with river water.
• D. Remains unchanged when algal bloom occurs.

Explanation: Biochemical oxygen demand (BOD) is the amount of oxygen taken up by microorganisms that decompose organic waste matter in water. It is therefore used as a measure of the amount of certain types of organic pollutant in water. Biochemical Oxygen Demand (BOD) typically increases when sewage gets mixed with river water. BOD is a measure of the amount of dissolved oxygen that microorganisms need to decompose organic matter in water. When sewage, which contains organic materials, is discharged into a river, it introduces a significant amount of organic matter into the water.

253. The montreal Protocol aims to:

• A. Conserve biodiversity
• B. Control water pollution
• C. Control CO2 emissions
• D. Reduce the use of ozone depleting substances

Explanation: The Montreal Protocol was signed in Montreal, Canada, by over 150 countries at a convention in 1987 to cut the use of CFCs (chlorofluoro­ carbons). The aim of the protocol was to protect the ozone layer in the stratosphere by decreasing and eventually eliminating the use of ozone-depleting substances like CFCs. It is regarded as one of the most successful international treaties in modern history.

254. DDT residues are rapidly passed through food chains causing biomagnification because DDT is:

• A. Moderately toxic
• B. Non­-toxic to aquatic animals
• C. Water soluble
• D. Liposoluble

Explanation: Biomagnification is caused by non­-degradable pollutants like DDT. Heavy metals and persistent pesticides (e.g., organochlorine or chlorinated hydrocarbons like DDT) pass into the food chain and increase in amount per unit weight of organisms with the rise in trophic level because they are liposoluble.

255. According to the Central Pollution Control Board (CPCB), which particulate size in diameter (in micrometres) of the air pollutants is responsible for the greatest harm to human health?

• A. 1.0 or less
• B. 2.5-5.2
• C. 2.5 or less
• D. 1.5 or less

Explanation: Particulate matter consists of soot, fly ash, dust, spores, pollen grains etc. Particulate matter is differentiated into settleable (larger than 10 mm and remaining in the air for less than one day) and suspended (less than 10 mm and remaining in the air for more than one day to several weeks). Particles of 2.5 μm and lesser diameter (PM 2.5) are the most harmful to human health (as per Central Pollution Control Board or CPCB). They pass deep into the lungs causing breathing and respiratory problems, irritation, inflammation and damage to the lungs resulting in pre­ mature death. It cannot directly enter the circulatory system but indirectly through the respiratory system.

256. In a coal fired power plant electrostatic precipitators are installed to control emission of:

• A. NO X
• B. SPM
• C. CO
• D. SO 2

Explanation: SPM is suspended particulate matter which is less than 10 mm remaining in air for more than one day to several weeks. It includes aerosol, dust, mist, smoke, soot etc. In a coal-fired power plant, electrostatic precipitators (ESPs) are commonly installed to control the emission of Suspended Particulate Matter (SPM) or particulate matter in the flue gas. SPM refers to fine ash, dust, and other solid particles that are generated during the combustion of coal. ESPs are effective air pollution control devices designed to capture and remove these airborne particulates before they are released into the atmosphere, helping to reduce the emission of SPM and improve air quality.

257. Photochemical smog pollution does not contain:

• A. PAN (peroxyacyl nitrate)
• B. Ozone
• C. Nitrogen dioxide
• D. Carbon dioxide

Explanation: Photochemical smog is a complex type of air pollution primarily formed through chemical reactions involving pollutants released into the atmosphere. While the composition of photochemical smog can vary, it typically contains a mix of pollutants and secondary compounds. Photochemical smog is formed at high temperatures over cities and towns due to still air, emission of nitrogen oxides and carbohydrates from automobile exhausts and solar energy.

258. Montreal protocol which calls for appropriate action to protect the ozone layer from human activities was passed in the year:

• A. 1985
• B. 1986
• C. 1987
• D. 1988

Explanation: The Montreal protocol was signed in Montreal, Canada, by over 150 countries at a convention in 1987 to cut use of CFCs (chlorofluoro­ carbons). The aim of the protocol was to protect the ozone layer in the stratosphere by decreasing and eventually eliminating the use of ozone depleting substances like CFCs. It is regarded as one of the most successful international treaties in modern history.

259. Prolonged liberal irrigation of agricultural fields is likely to create the problem of:

• A. Acidity
• B. Aridity
• C. Salinity
• D. Metal toxicity

Explanation: Irrigation induced salinity can arise as a result of the use of any irrigation water, irrigation of saline water etc. combined with inadequate leaching. Since all surface and ground water contains salts to varying degrees, irrigation is often seen as the primary culprit for bringing salts into the field.

260. Which one of the following is not used for disinfection of drinking water?

• A. Chlorine
• B. Ozone
• C. Chlorine dioxide
• D. Phenyl

Explanation: Chlorine is one of the most widely used disinfectants for water treatment. It is effective at killing a wide range of microorganisms and has a residual effect, providing continued protection as water flows through the distribution system. However, excessive chlorination can lead to the formation of disinfection byproducts (DBPs), some of which are of concern for health.