Answers and bookmarks are saved in this browser, across visits. They do not sync to your account.
100 questions in this collection · Page 1 of 10
Question 1 of 100
📘 CLASS XII
Environmental Issues
Consider the following statements regarding the Electrostatic Precipitator:
I. It can remove over 99 percent of particulate matter present in the exhaust from a thermal power plant. II. The electrode wires are maintained at several thousand volts, which produce a corona that releases protons. III. Dust particles get a net positive charge when they pass through the corona. IV. The velocity of air between the collecting plates must be low enough to allow the dust to fall.
Which of the statements given above are correct?
The electrostatic precipitator removes over 99% of particulate matter from industrial exhaust. The electrode wires release electrons (not protons), giving dust particles a net negative charge. The air velocity between the plates must be sufficiently low to allow the dust particles to settle.
Question 2 of 100
📘 CLASS XII
Environmental Issues
With reference to the Scrubber used in controlling air pollution, consider the following statements:
I. A scrubber is highly effective in removing gases like sulfur dioxide from industrial exhaust. II. In a scrubber, the exhaust is passed through a spray of water or lime. III. The lime spray reacts with SO2 to form precipitates of calcium compounds. IV. A scrubber is primarily used to oxidize unburnt hydrocarbons in vehicular emissions.
Which of the statements given above are correct?
Scrubbers remove sulfur dioxide by passing exhaust through a spray of water or lime. Lime reacts with SO2 to form calcium compounds. Oxidation of carbon monoxide and unburnt hydrocarbons is performed by catalytic converters, not scrubbers.
Question 3 of 100
📘 CLASS XII
Environmental Issues
Consider the following statements about Catalytic Converters:
I. They use expensive metals like platinum, palladium, and rhodium as catalysts. II. As the exhaust passes through, nitric oxide (NO) is changed into nitrogen gas (N2) and oxygen. III. Carbon monoxide (CO) and unburnt hydrocarbons are converted into carbon dioxide (CO2) and water (H2O). IV. Vehicles equipped with catalytic converters must use unleaded petrol because lead inactivates the catalyst.
Which of the statements given above are correct?
All the statements are correct. Catalytic converters use platinum, palladium and rhodium to convert harmful gases into less harmful products. Leaded petrol must not be used because lead inactivates the catalyst.
Question 4 of 100
📘 CLASS XII
Environmental Issues
Read the following statements regarding air pollution legislation in India:
I. In India, the Air (Prevention and Control of Pollution) Act came into force in 1981. II. The Air Act was amended in 1987 to include noise as an air pollutant. III. Brief exposure to an extremely high sound level of 150 dB or more can permanently damage eardrums. IV. Delhi's air quality steadily deteriorated between 1997 and 2005 due to the failure of emission acts.
Which of the statements given above are correct?
The Air Act came into force in 1981 and was amended in 1987 to include noise. Exposure to 150 dB or above may permanently damage eardrums. Delhi's air quality improved significantly between 1997 and 2005 due to mandatory CNG conversion.
Question 5 of 100
📘 CLASS XII
Environmental Issues
Analyze the following measures proposed for controlling noise pollution:
I. Muffling industrial noise and utilizing sound-absorbent materials in factory walls. II. Delimitation of horn-free zones around hospitals and educational institutes. III. Creating strict legal guidelines for permissible sound levels of crackers and loudspeakers. IV. Setting strict timing restrictions after which loudspeakers cannot be played.
Which of the statements given above represent valid noise control measures?
All four measures are standard methods of controlling noise pollution, including soundproofing, horn-free zones, permissible sound limits, and restrictions on loudspeaker timings.
Question 6 of 100
📘 CLASS XII
Environmental Issues
Consider the following statements regarding Delhi's historic switch to Compressed Natural Gas (CNG):
I. In the 1990s, Delhi ranked fourth among the 41 most polluted cities in the world. II. Under Supreme Court directives, all public transport buses in Delhi were transitioned to run on CNG by the end of 2002. III. CNG is preferred because it burns more efficiently than petrol or diesel, leaving very little unburnt. IV. CNG is cheaper than diesel, but its main drawback is that it can easily be siphoned off by thieves and adulterated.
Which of the statements given above are correct?
Statement IV is incorrect because CNG cannot be easily siphoned off or adulterated, which is one of its major advantages. Statements I, II and III are correct.
Question 7 of 100
📘 CLASS XII
Environmental Issues
With reference to fuel and emission norms in India, consider the following statements:
I. The Government of India framed the Auto Fuel Policy to systematically reduce sulfur and aromatic contents in petrol and diesel. II. Mass emission standards (Bharat Stage IV) were made applicable to 3-wheelers and 2-wheelers throughout the country since April 2017. III. These fuel standards aim to transition vehicles towards cleaner, low-emission technologies.
Which of the statements given above are correct?
All three statements are correct. The Auto Fuel Policy reduced sulfur and aromatic contents in fuels, Bharat Stage IV norms became applicable nationwide in April 2017, and the standards promote cleaner vehicle technologies.
Question 8 of 100
📘 CLASS XII
Environmental Issues
The following statements describe the composition of domestic sewage:
I. A mere 0.1 percent impurities make domestic sewage completely unfit for human use. II. Sand, silt, and clay represent the colloidal material present in sewage. III. Fecal matter, bacteria, paper, and textile fibers constitute the suspended solids. IV. Dissolved materials in sewage include plant nutrients like nitrates, ammonia, phosphate, sodium, and calcium.
Which of the statements given above are correct?
Statement II and III are incorrect because their categories are interchanged. Suspended solids include sand, silt and clay, while colloidal materials include fecal matter, bacteria, paper and textile fibres. Dissolved materials include nitrates, ammonia, phosphate, sodium and calcium.
Question 9 of 100
📘 CLASS XII
Environmental Issues
Consider the following statements regarding Biochemical Oxygen Demand (BOD):
I. BOD measures the amount of biodegradable organic matter present in sewage water. II. At the point of sewage discharge into a river, the BOD rises sharply. III. A sharp rise in BOD is accompanied by a dramatic increase in the dissolved oxygen (DO) levels of the water body. IV. Decomposing micro-organisms utilize organic substances as substrates, consuming oxygen in the process.
Which of the statements given above are correct?
BOD measures the amount of biodegradable organic matter present in sewage. When sewage enters a water body, microorganisms consume oxygen while decomposing organic matter, causing BOD to rise and dissolved oxygen (DO) to decrease. Therefore, Statement III is incorrect.
Question 10 of 100
📘 CLASS XII
Environmental Issues
Read the following statements about Algal Blooms in water bodies:
I. Large amounts of nutrients in water cause excessive, free-floating growth of planktonic algae. II. Algal blooms impart a distinct color to the water body. III. Algal blooms lead to a deterioration in water quality and cause heavy fish mortality. IV. Some bloom-forming algae are highly toxic to humans and domestic animals.
Which of the statements given above are correct?
All the statements are correct. Nutrient enrichment causes algal blooms, which discolor water, reduce water quality, deplete oxygen leading to fish mortality, and some bloom-forming algae produce toxins harmful to humans and domestic animals.