Sources of Pollution - Questions & Answers

1. Direct sources of pollutants that are easy to identify, monitor and control:
(c) Point sources

2. Which amongst the following is not a source of Noise Pollution?
(d) Burning of Garbage

3. Ozone, ketones and sulphur oxides are examples of (c) Secondary Pollutants.

4. Suspended droplets, solid particles or mixtures of both, in air are called (d) Particulate air pollutants.

5. Which amongst the following is NOT a source of Air Pollution?
(b) Biomedical Waste

6. Motor vehicles fuel, burning of wood, coal and solid waste disposal are major sources of which pollutant?
(a) Carbon monoxide

7. Rapid growth of algae when phosphates are discharged into waterways.
(b) Eutrophication

8. Assertion (A): The rapidly increasing number of vehicles on the roads is a big source of noise pollution.
Reason (R): Increasing traffic jams in congested areas lead to repeated hooting of horns by impatient drivers causing noise pollution.
(a) Both A and R are true and R is the correct explanation of A.

9. Assertion (A): Noise from construction sites is generally far worse than noise originating from factories.
Reason (R): Construction itself causes high noise emissions and the equipment used is inherently noisy.
(a) Both A and R are true and R is the correct explanation of A.

10. Which amongst the following is not a source of Radioactive Pollution?
(c) Pesticides

11. Construction sites are source of which pollution?
(d) Only (a) and (b)

12. Assertion (A): The excessive use of chemical fertilisers creates pollution.
Reason (R): The fertilisers are used to enrich the soil.
(b) Both A and R are true but R does not explain A.

Given below are scenes, list the main pollutants for each and identify which type of pollution each causes. Give reasons to support your answers.

Scene (a): Vehicles stuck in a traffic jam.
Main Pollutants: Carbon monoxide, nitrogen oxides, unburnt hydrocarbons, and noise.
Type of Pollution: Air Pollution and Noise Pollution.
Reasons: The fuel combustion from automobiles releases harmful gases into the air, while the repeated hooting of horns by impatient drivers in congested areas creates significant noise pollution.

Scene (b): A construction site with heavy machinery and pipes.
Main Pollutants: Particulate matter (dust), suspended solids, and intense noise.
Type of Pollution: Air Pollution and Noise Pollution.
Reasons: The construction equipment is inherently noisy, causing severe noise emissions. Additionally, excavation and building material production release a massive amount of dust and particulate matter into the surrounding atmosphere.

1. Name any three air pollutants and the sources of each of them.
(i) Carbon Monoxide (CO): Sourced from motor vehicles fuel and burning of wood/coal.
(ii) Nitrogen Oxides (NOx): Sourced from motor vehicles and power generation stations.
(iii) Sulphur Oxides (SOx): Sourced from the burning of coal and refineries.

2. What are natural sources of air pollution? Name one industry which pollutes the atmosphere with gaseous as well as with particulate matter.
Natural sources include volcanic eruptions, deflation of sand and dust, and wild fires of natural vegetation. Cement factories and thermal power plants are industries that pollute the atmosphere with both gaseous and particulate matter (dust and smoke).

3. What is known as smog? What harm is done by smog especially in winter?
A combination of smoke and fog is known as smog. In winter, smog creates severe health hazards such as asthma, bronchitis, shortness of breath, and eye and nose irritation. It also reduces visibility, leading to serious traffic movement problems.

4. Name three gases emitted during burning of garbage.
Carbon dioxide, sulphur dioxide, and nitrogen oxides.

5. Mention any two sources of water pollution.
(i) Domestic waste (municipal wastewater containing detergents and sewage).
(ii) Industrial waste (discharge from chemical, paper, and food processing industries).

6. Name two heavy metals from industries that pollute water.
Lead and Mercury.

7. Mention any two sources of soil pollution.
(i) Excessive use of chemical fertilisers.
(ii) Improper dumping of biomedical waste.

8. Why are radioactive pollutants very dangerous?
They are extremely hazardous to living organisms because radioactive emissions can pass through genetic cells and affect the chromosomes, resulting in mutations. They also absorb into aquatic organisms and accumulate through food chains, eventually passing on to human beings.

9. In cities flyovers are constructed with large sheets of fibre glass on the outer side of the flyovers. Give reason.
These large sheets act as sound barriers. They help to contain and reflect the vehicular traffic noise, significantly reducing the noise pollution experienced by people living in the nearby residential areas.

10. How does lighting of crackers cause pollution?
Lighting crackers causes both air and noise pollution. The explosions generate intensely loud, unwanted noise, and the burning chemicals release harmful gases and heavy particulate matter (smoke and ash) into the atmosphere.

1. With reference to noise pollution, answer the following:
(a) When does sound become a source of noise pollution?
Sound becomes a source of noise pollution when it turns into unwanted sound that produces unpleasant effects, discomfort, and interferes with normal activities such as sleeping, conversation, or disrupts one's quality of life.

(b) How does traffic contribute to noise pollution?
The rapidly increasing number of vehicles on the roads is a massive source of noise. In congested areas, increasing traffic jams lead to repeated and excessive hooting of horns by impatient drivers, contributing heavily to noise pollution.

(c) Why are the construction sites considered worse than factories in their contribution to noise pollution?
Construction sites are worse because the construction process itself causes incredibly high noise emissions. Demolition and repair activities use huge machines, and the equipment used is inherently noisy and often operates out in the open.

(d) How do airplanes cause noise pollution? Why is there more noise pollution during landing as compared to during take-off?
Airplanes cause noise due to the violent mixing of jet gases from the engine with the surrounding air, and from the air compressors and turbine blades. Take-off noise is at maximum level but reduces rapidly as the aircraft climbs. During landing, however, the aircraft passes close to the ground for quite a distance, meaning the high-frequency noise from compressors and turbines constitutes a more sustained environmental nuisance than the shorter duration noise of take-off.

2. Air pollution is the contamination of air by pollutants. In this context answer the following:
(a) Based on their origin, how can air pollutants be classified?
They can be classified into Primary Pollutants (emitted directly from sources, e.g., ash, smoke, oxides of sulphur) and Secondary Pollutants (formed in the atmosphere by chemical interactions between primary pollutants, e.g., ozone, sulphur trioxide).

(b) How does the use of automobiles cause air pollution?
Automobiles are responsible for more than 80 per cent of total air pollution. Fuel combustion in vehicles releases massive amounts of carbon monoxide, unburnt hydrocarbons, and nitrogen oxides into the atmosphere, which further react in sunlight to form harmful secondary pollutants.

(c) How do industries pollute the air?
Industries such as chemical plants, cotton mills, and petroleum refineries emit fine dust, smoke, and hazardous gases like sulphur dioxide. These emissions mix in the air, creating health hazards, acid rain, and leading to the formation of dense winter smog.

(d) Mention any three air pollutants and two sources of each.
1. Carbon Monoxide: Motor vehicles fuel, burning of wood and coal.
2. Nitrogen Oxides: Motor vehicles, furnace stacks/incinerators.
3. Particulates: Fuel combustion, solid waste disposal.

3. With reference to the sources of water pollutants answer the following questions:
(a) What are the domestic sources of water pollution?
Domestic sources include used wastewater from drinking, bathing, and cleaning that is drained through municipal drains into rivers or lakes. This water is mixed with plastics, detergents, animal dung, and human faecal material, collectively known as municipal waste.

(b) Why is it harmful to dispose of household detergents in water bodies?
Many household detergents contain phosphates. When discharged into waterways, these phosphates enrich the water and promote the rapid growth of algae (a process called eutrophication). These aquatic weeds multiply quickly and interfere with fishing, navigation, and irrigation.

(c) In what way does the industrial waste pollute water?
Industries produce waste material such as heavy metals (cadmium, lead, mercury) and synthetic organic compounds. These highly toxic substances reach water bodies either through direct discharge or by leaching from waste dumps, accumulating in the biological system and aquatic life.

(d) What are the sources of radioactive pollution? Describe each of them.
The sources are:
1. Natural Sources: Cosmic rays with energetic radiations reaching earth from outer space.
2. X-rays Waste: Medical radiation used to detect disorders, which can pass through genetic cells and cause mutations.
3. Radioactive Fallout from Nuclear Plants: Escaped radioactive wastes, radiation, and inert gases from atomic reactors polluting the surroundings and soil.
4. Nuclear Weapons: Testing involves using radioactive substances like Uranium 235 and Plutonium 239, making surrounding materials radioactive.
5. Radioactive Isotopes: Used in research laboratories; their wastewater drastically pollutes local rivers and streams through sewers.

1. Of all the different types of pollution, noise pollution is the most subtle but with many harmful effects. Do you agree with this statement? Give reasons to support your answer.
Yes, I agree. Unlike air or water pollution, noise pollution is "subtle" because it is invisible, leaves no physical residue, and dissipates once the source stops. However, its harmful effects are continuous and severe. Prolonged exposure causes deep psychological and physiological stress, chronic discomfort, annoyance, and disrupts essential restorative activities like sleeping and conversation, ultimately severely deteriorating one's overall quality of life.

2. Pollution in the cities is the price of growing affluence. Give your views on the above statement with examples.
This statement is highly accurate. Growing affluence leads to increased purchasing power, rapid urbanization, and a higher standard of living, which directly translates to environmental degradation. For example, higher affluence means more people can afford private vehicles, leading to massive traffic jams and severe vehicular air and noise pollution. Increased wealth also drives up the demand for consumer goods, accelerating industrial production (which causes industrial smoke/effluents) and resulting in a much higher per capita generation of domestic garbage, plastics, and electronic waste.

Find out the percentage of pollutants released into the air by automobiles in your city. Do you think introduction of (a) CNG and (b) electric vehicles in some of the cities has been helpful in reducing pollution levels?
(Note: City percentages vary, but as a general geographical observation for Indian metropolises, automobiles account for nearly 70-80% of total air pollution).
Yes, the introduction of both CNG and electric vehicles has been exceptionally helpful in reducing pollution levels. CNG (Compressed Natural Gas) burns much cleaner than traditional fossil fuels like petrol or diesel, drastically reducing emissions of carbon monoxide, unburnt hydrocarbons, and suspended particulate matter. Electric vehicles are even better as they produce zero tailpipe emissions and run silently, meaning they simultaneously help eliminate both urban air pollution and vehicular noise pollution.