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100 questions in this collection · Page 6 of 10
Question 51 of 100
📘 CLASS XII
Environmental Issues
Consider the following statements regarding the operation of an 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 to produce a corona. III. The corona releases neutrons that attach to dust particles, giving them a net neutral charge. IV. The collecting plates are positively charged and actively repel the negatively charged dust particles.
Which of the statements given above are correct?
The electrostatic precipitator removes over 99% of particulate matter. Electrode wires maintained at several thousand volts produce a corona that releases electrons, giving dust particles a negative charge. The collecting plates are grounded, not positively charged. Hence Statements III and IV are incorrect.
Question 52 of 100
📘 CLASS XII
Environmental Issues
Read the following statements regarding the deleterious effects of air pollution:
I. Air pollutants cause injury to all living organisms, reducing the growth and yield of crops. II. They cause the premature death of plants. III. Harmful effects of air pollutants depend on the concentration of pollutants and the duration of exposure. IV. The harmful effects of air pollutants are independent of the species of organism exposed.
Which of the statements given above are correct?
Air pollutants injure living organisms, reduce crop yield, and may cause premature death of plants. Their harmful effects depend on pollutant concentration, duration of exposure, and the species of organism exposed. Hence Statement IV is incorrect.
Question 53 of 100
📘 CLASS XII
Environmental Issues
With reference to the Scrubber used in industrial exhaust systems, consider the following statements:
I. A scrubber is primarily used to remove gaseous pollutants like sulphur dioxide. II. In a scrubber, the exhaust is passed through a spray of water or lime. III. The lime spray reacts with sulphur dioxide to form precipitates of calcium compounds. IV. Modern scrubbers are highly effective at completely removing particulate matter smaller than 2.5 micrometers (PM 2.5).
Which of the statements given above are correct?
Scrubbers remove gaseous pollutants such as sulphur dioxide by passing exhaust through water or lime spray. Lime reacts with SO2 to form calcium compounds. Standard scrubbers are not effective at removing extremely fine PM2.5 particles, making Statement IV incorrect.
Question 54 of 100
📘 CLASS XII
Environmental Issues
Consider the following statements regarding the use of Catalytic Converters in automobiles:
I. They contain expensive catalytic metals namely platinum-palladium and rhodium. II. As exhaust passes through, unburnt hydrocarbons are converted into carbon dioxide and water. III. Motor vehicles equipped with catalytic converters must use leaded petrol because lead activates the catalysts. IV. Nitric oxide is changed into nitrogen gas, and carbon monoxide is changed into carbon dioxide.
Which of the statements given above are correct?
Catalytic converters use platinum, palladium and rhodium to convert CO, hydrocarbons and NO into less harmful products. Vehicles equipped with catalytic converters must use unleaded petrol because lead poisons and inactivates the catalysts. Hence Statement III is incorrect.
Question 55 of 100
📘 CLASS XII
Environmental Issues
Read the following statements regarding the impacts of Noise Pollution:
I. The Air (Prevention and Control of Pollution) Act came into force in 1981 but was amended in 1987 to include noise as an air pollutant. II. A brief exposure to extremely high sound levels of 150 dB or more may permanently damage ear drums. III. Even chronic exposure to relatively lower noise levels in cities can permanently damage human hearing abilities. IV. Noise pollution is associated with sleeplessness, an increased heart rate, and altered breathing patterns.
Which of the statements given above are correct?
All four statements are correct. The Air Act was amended in 1987 to include noise pollution. Excessive and prolonged noise exposure damages hearing and causes physiological stress including sleeplessness, increased heart rate and altered breathing patterns.
Question 56 of 100
📘 CLASS XII
Environmental Issues
With reference to the case study on controlling vehicular air pollution in Delhi, read the following statements:
I. In the 1990s, Delhi ranked fourth among the 41 most polluted cities of the world. II. Air pollution in Delhi became so severe that a public interest litigation (PIL) was filed in the Supreme Court of India. III. The Supreme Court directed the government to convert the entire fleet of public transport buses from diesel to CNG. IV. All the public transport buses of Delhi were successfully transitioned to run on CNG by the end of 2005.
Which of the statements given above are correct?
Statements I, II and III are correct. Delhi converted its entire public bus fleet to CNG by the end of 2002, not 2005. Hence Statement IV is incorrect.
Question 57 of 100
📘 CLASS XII
Environmental Issues
Analyze the following statements about Compressed Natural Gas (CNG):
I. CNG burns most efficiently in automobiles, leaving very little unburnt. II. CNG is cheaper than petrol or diesel. III. Its main advantage is that it can easily be siphoned off by thieves and adulterated. IV. The primary difficulty with switching to CNG is laying pipelines to deliver it through distribution pumps.
Which of the statements given above are correct?
CNG burns efficiently, is cheaper than petrol or diesel, and cannot be siphoned off or adulterated. The major challenge is laying an adequate pipeline network for uninterrupted supply. Therefore Statement III is incorrect.
Question 58 of 100
📘 CLASS XII
Environmental Issues
Consider the following statements regarding the Auto Fuel Policy and Euro norms:
I. More stringent norms for fuels mean steadily reducing the sulphur and aromatic content in petrol and diesel. II. Euro III norms stipulate that sulphur be controlled at 350 ppm in diesel and 150 ppm in petrol. III. Under Euro III, aromatic hydrocarbons are to be contained at 42 percent of the concerned fuel. IV. The ultimate target of the roadmap is to reduce sulphur to 150 ppm in petrol and diesel.
Which of the statements given above are correct?
Statements I, II and III are correct. The long-term target is to reduce sulphur content to 50 ppm in both petrol and diesel while reducing aromatic hydrocarbons to 35%. Hence Statement IV is incorrect.
Question 59 of 100
📘 CLASS XII
Environmental Issues
With reference to water pollution legislation and the properties of domestic sewage, consider the following statements:
I. The Government of India passed the Water (Prevention and Control of Pollution) Act in 1974. II. A mere 0.1 percent impurities make domestic sewage completely unfit for human use. III. Suspended solids in sewage include nitrates, ammonia, phosphates, sodium, and calcium. IV. Domestic sewage contains biodegradable organic matter, which is decomposed by bacteria and fungi.
Which of the statements given above are correct?
Statements I, II and IV are correct. Nitrates, ammonia, phosphates, sodium and calcium are dissolved substances, whereas suspended solids include sand, silt and clay. Therefore Statement III is incorrect.
Question 60 of 100
📘 CLASS XII
Environmental Issues
Read the following statements regarding Biochemical Oxygen Demand (BOD) and sewage discharge:
I. The amount of biodegradable organic matter in sewage water can be estimated by measuring BOD. II. Micro-organisms involved in biodegradation of organic matter consume a lot of oxygen. III. Following sewage discharge, there is a sharp increase in dissolved oxygen downstream from the discharge point. IV. Decline in dissolved oxygen downstream leads to the mortality of fish and other aquatic creatures.
Which of the statements given above are correct?
Biochemical Oxygen Demand (BOD) estimates the amount of biodegradable organic matter in sewage. During decomposition, microorganisms consume large quantities of oxygen, causing a sharp decline in dissolved oxygen (DO) downstream of sewage discharge. Reduced DO results in the death of fish and other aquatic organisms. Hence, Statement III is incorrect.