Sources of Pollution

Direct sources of pollutants that are easy to identify, monitor and control:

1. Direct sources
2. Primary sources
3. Point sources
4. Secondary sources

Answer

Point sources

Reason — Point sources are direct and identifiable sources of pollution that can be easily located, monitored, and controlled. Examples include emissions from factory chimneys, sewage discharge pipes, and power plants.

Which amongst the following is not a source of Noise Pollution?

1. Traffic
2. Factories
3. Defence
4. Burning of Garbage

Answer

Burning of Garbage

Reason — Traffic, factories, and defence activities are major sources of noise pollution. Burning of garbage is a source of air pollution, as it releases harmful gases and particulate matter into the atmosphere, not noise.

Ozone, ketones and sulphur oxides are examples of ............... .

1. Primary Pollutants
2. Direct Pollutants
3. Secondary Pollutants
4. Natural Pollutants

Answer

Secondary Pollutants

Reason — Secondary pollutants are the pollutants that are formed in the atmosphere by chemical interactions between primary pollutants and atmospheric constituents. Sulphur trioxide, ozone, Peroxyacetyl Nitrate (PAN) and ketones are examples of secondary pollutants.

Suspended droplets, solid particles or mixtures of both, in air are called ............... .

1. Gaseous air pollutants
2. Natural air pollutants
3. Primary pollutants
4. Particulate air pollutants

Answer

Particulate air pollutants

Reason — Based on their state of matter, air pollutants are classified as gaseous and particulate pollutants. Particulate air pollutants consist of suspended solid particles, liquid droplets, or a mixture of both, and include dust, smoke, soot, fumes, and fly ash.

Which amongst the following is NOT a source of Air Pollution?

1. Vehicular exhaust
2. Biomedical Waste
3. Industrial exhaust
4. Burning of garbage

Answer

Biomedical Waste

Reason — The major sources of air pollution include vehicular exhaust, industrial emissions, and the burning of garbage. Biomedical waste is primarily a source of soil and land pollution if not disposed of properly. Hence, it is not considered a direct source of air pollution in this context.

Motor vehicles fuel, burning of wood, coal and solid waste disposal are major sources of which pollutant?

1. Carbon monoxide
2. Nitrogen oxides
3. Particulates
4. Sulphur oxides

Answer

Carbon monoxide

Reason — The sources of carbon monoxide (CO) are gasoline fuel, motor vehicles fuel, burning of wood and coal, solid waste disposal and industrial processes.

Rapid growth of algae when phosphates are discharged into waterways.

1. Algae-Discharge
2. Eutrophication
3. Algae-Enrichment
4. Phosphatic Algae

Answer

Eutrophication

Reason — Eutrophication is the process by which water bodies become enriched with nutrients, especially phosphates from detergents and fertilizers. This promotes the rapid growth of algae and aquatic weeds, which depletes dissolved oxygen and interferes with fishing, navigation, and irrigation.

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.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R does not explain A.
3. A is true but R is false.
4. A is false but R is true.

Answer

Both A and R are true and R is the correct explanation of A.

Explanation — The rapidly increasing number of vehicles on the roads is a major source of noise pollution. Increasing traffic jams in congested areas lead to frequent honking of horns by impatient drivers, which significantly increases noise levels.

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.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R does not explain A.
3. A is true but R is false.
4. A is false but R is true.

Answer

Both A and R are true and R is the correct explanation of A.

Explanation — Noise from construction sites is generally greater than that from factories because construction activities generate high noise levels, and the machinery and equipment used are inherently noisy.

Which amongst the following is not a source of Radioactive Pollution?

1. Nuclear weapons
2. X-rays waste
3. Pesticides
4. Radioactive fallout from nuclear plants

Answer

Pesticides

Reason — Sources of radioactive pollution include X-ray waste, radioactive fallout from nuclear plants, nuclear weapons, and radioactive isotopes. Pesticides contaminate the soil and are therefore a source of soil pollution, not radioactive pollution.

Construction sites are source of which pollution?

1. Noise due to construction equipment.
2. Air due to the particulate matter released.
3. Soil due to the excavation for the site.
4. Only (1) and (2).

Answer

Only (1) and (2).

Reason — Construction sites cause noise pollution due to the use of heavy machinery and equipment, and air pollution due to the release of dust and particulate matter. They are not considered a direct source of soil pollution.

Assertion (A): The excessive use of chemical fertilisers creates pollution.

Reason (R): The fertilisers are used to enrich the soil.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R does not explain A.
3. A is true but R is false.
4. A is false but R is true.

Answer

Both A and R are true but R does not explain A.

Explanation — Chemical fertilisers are used to enrich the soil by supplying plant nutrients. However, their excessive use contaminates the soil and nearby water bodies, causing pollution. Thus, both the Assertion and Reason are true, but the Reason does not explain why excessive use of fertilisers creates pollution.

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

Picture A

Picture B

Answer

(a) The main pollutants in Picture A are —

1. Carbon monoxide (CO)
2. Unburnt hydrocarbons
3. Nitrogen monoxide (NO)

These pollutants are released from the incomplete combustion of fuel in automobile engines, causing vehicular air pollution.

Reasons —

1. Carbon monoxide reduces the oxygen-carrying capacity of the blood.

2. Unburnt hydrocarbons contribute to the formation of photochemical smog.

3. Nitrogen monoxide reacts with oxygen to form nitrogen dioxide (NO₂), a harmful air pollutant.

(b) The main pollutants in picture B are —

1. Smoke
2. Particulate matter (dust)
3. Sulphur dioxide (SO₂)
4. Nitrogen oxides (NOₓ)
5. Carbon monoxide (CO)

These pollutants cause air pollution.

Reasons —

1. Construction material industries release dust and particulate matter during crushing, grinding, and processing.

2. Burning fossil fuels in factories emits smoke, sulphur dioxide, nitrogen oxides, and carbon monoxide.

3. These pollutants reduce air quality, cause respiratory diseases, and contribute to smog and acid rain.

Name any three air pollutants and the sources of each of them.

Answer

Three air pollutants are-

1. Carbon Monoxide — It is produced by gasoline fuel, motor vehicles fuel, burning of wood and coal, solid waste disposal and industrial processes.

2. Nitrogen Oxides — Its primary sources are motor vehicles and power generation stations, combustion of organic matters, furnace stacks and incinerators.

3. Hydrocarbons — These are produced by motor vehicles, industrial processes, garbage and agricultural waste.

What are natural sources of air pollution? Name one industry which pollutes the atmosphere with gaseous as well as with particulate matter.

Answer

Natural sources of air pollution produce air pollutants as a result of natural phenomena. These include volcanic eruptions, deflation of sand and dust as well as forest, or wild fires of natural vegetation, etc.

Automobile industry pollutes the atmosphere with gaseous as well as with particulate matter.

What is known as smog? What harm is done by smog especially in winter?

Answer

Smog is a combination of smoke and fog.

During winter, the increased burning of coal and other fossil fuels for heating, along with fog, leads to the formation of smog. Smog is harmful because it causes asthma, bronchitis, shortness of breath, and irritation of the eyes and nose. It also reduces visibility, causing traffic and transport problems.

Name three gases emitted during burning of garbage.

Answer

Three gases emitted during burning of garbage are-

1. Carbon dioxide
2. Sulphur dioxide
3. Nitrogen oxides

Mention any two sources of water pollution.

Answer

Two sources of water pollution are-

1. Domestic sources, like phosphates from detergents and fertilisers.
2. Industrial sources, like heavy metals and synthetic organic compounds.

Name two heavy metals from industries that pollute water.

Answer

Two heavy metals from industries that pollute water are-

1. Lead
2. Manganese

Mention any two sources of soil pollution.

Answer

Two sources of soil pollution are-

1. Chemical fertilisers
2. Biomedical waste

Why are radioactive pollutants very dangerous?

Answer

Radioactive pollutants are very dangerous because-

1. Radioactive wastes from nuclear reactors are hazardous to all living organisms.
2. Radioactive wastes may leak into the environment even after being buried underground, while radioactive gases can escape into the atmosphere.
3. Nuclear weapon tests release radioactive materials that contaminate the environment.
4. Radioactive particles are carried by wind and rain to distant places, polluting the soil and water.
5. These pollutants enter the food chain through plants and aquatic organisms and ultimately affect human beings.

In cities flyovers are constructed with large sheets of fibre glass on the outer side of the flyovers. Give reason.

Answer

Large fibreglass sheets are installed along flyovers to reduce noise pollution. They act as sound barriers, absorbing and blocking the noise produced by heavy vehicular traffic, thereby reducing its impact on nearby residential and commercial areas.

How does lighting of crackers cause pollution?

Answer

Lighting of crackers significantly contributes to Air Pollution and Noise pollution.

1. Air Pollution: Crackers release harmful gases like sulphur dioxide, nitrogen oxides, carbon monoxide, and particulate matter into the atmosphere. These reduce air quality and can cause respiratory issues.

2. Noise Pollution: Loud explosions from crackers exceed safe decibel levels, causing hearing discomfort, stress, and disturbance to humans and animals.

With reference to noise pollution, answer the following:

When does sound become a source of noise pollution?

Answer

Noise pollution refers to an unwanted sound which produces unpleasant effects and discomfort. Sound becomes unwanted when it interferes with normal activities such as sleeping, conversation or disrupts one's quality of life.

With reference to noise pollution, answer the following:

How does traffic contribute to noise pollution?

Answer

The rapidly increasing number of vehicles on the roads are a big source of noise pollution. Increasing traffic jams in congested areas lead to repeated hooting of horns by impatient drivers causing noise pollution.

With reference to noise pollution, answer the following:

Why are the construction sites considered worse than factories in their contribution to noise pollution?

Answer

Construction sites are considered worse than factories in their contribution to noise pollution because construction activities generate very high noise levels, and the machinery and equipment used are inherently noisy.

Moreover, in the era of rapid urbanisation, construction, demolition, and repair activities, along with the use of heavy machines, create excessive noise, causing inconvenience and disturbance to people living nearby.

With reference to noise pollution, answer the following:

How do airplanes cause noise pollution? Why is there more noise pollution during landing as compared to during take-off?

Answer

Airplanes cause noise pollution because jet aircraft produce much louder and higher-pitched noise than propeller-driven aircraft. Jet noise is caused by the violent mixing of hot gases from the engine with the surrounding air. The noise is greatest during take-off, when the engines produce maximum thrust.

During landing, aircraft fly close to the ground for a longer distance. In addition, noise from the air compressor and turbine blades is prominent. As a result, people on the ground are exposed to noise for a longer duration, making landing a greater source of noise pollution than take-off.

Air pollution is the contamination of air by pollutants. In this context answer the following:

Based on their origin, how can air pollutants be classified?

Answer

Air pollutants can be classified as-

1. Primary Pollutants
2. Secondary Pollutants

Air pollution is the contamination of air by pollutants. In this context answer the following:

How does the use of automobiles cause air pollution?

Answer

Automobiles are a major source of air pollution. They release harmful pollutants such as carbon monoxide (CO), unburnt hydrocarbons, nitrogen oxides (NOₓ), and suspended particulate matter due to the combustion of fuel.

Some hydrocarbons react with sunlight and nitrogen oxides to form photochemical oxidants such as ozone, which are harmful to human health and the environment. Thus, vehicular emissions significantly degrade air quality.

Air pollution is the contamination of air by pollutants. In this context answer the following:

How do industries pollute the air?

Answer

Industries such as chemical industries, paper and pulp mills, cotton mills, petroleum refineries, cement factories, and thermal power plants are major sources of air pollution.

Factories emit smoke, dust, particulate matter, carbon, sulphur dioxide (SO₂), and other harmful gases, which pollute the air. Cement factories release large amounts of dust, while thermal power plants burning coal or heavy oil emit sulphur dioxide, which reacts with oxygen and water vapour to form sulphuric acid, causing acid rain and health hazards.

Air pollution is the contamination of air by pollutants. In this context answer the following:

Mention any three air pollutants and two sources of each.

Answer

Three air pollutants are-

1. Carbon monoxide — It is produced by gasoline fuel and motor vehicles fuel.
2. Nitrogen oxides — Its primary sources are motor vehicles and power generation stations.
3. Hydrocarbons — These are produced by motor vehicles and industrial processes.

With reference to the sources of water pollutants answer the following questions:

What are the domestic sources of water pollution?

Answer

Domestic sources of water pollution include municipal sewage and household wastewater generated from drinking, cooking, bathing, washing clothes and utensils, and cleaning houses. This wastewater, containing detergents, soaps, plastics, human excreta, animal waste, and other domestic refuse, is often discharged into rivers and lakes, causing water pollution.

Phosphate-containing detergents also pollute water by promoting the rapid growth of algae, a process known as eutrophication.

With reference to the sources of water pollutants answer the following questions:

Why is it harmful to dispose of household detergents in water bodies?

Answer

Many detergents contain phosphates. When phosphates are discharged into waterways, their remnants promote rapid growth of algae. Such enrichment process is known as eutrophication. Aquatic weeds multiply rapidly in many water bodies. They interfere with fishing, navigation and irrigation.

With reference to the sources of water pollutants answer the following questions:

In what way does the industrial waste pollute water?

Answer

Industries such as chemical, pulp and paper, and food-processing industries discharge waste containing heavy metals (such as lead, mercury, cadmium, and chromium) and synthetic organic compounds into water bodies, either directly or through leaching from waste dumps.

These pollutants make water poisonous and unfit for use, harm aquatic life, and may cause diseases in humans and animals if the contaminated water is consumed without treatment.

With reference to the sources of water pollutants answer the following questions:

What are the sources of radioactive pollution? Describe each of them.

Answer

The two main sources of radioactive pollution are-

1. Natural sources — Cosmic rays from outer space emit energetic radiations. Although they are hazardous in space, they are generally not harmful to organisms on Earth because the atmosphere provides protection.
2. Man made sources —
   1. X-rays waste — X-rays and radioactive isotopes used in medicine may damage genetic cells and cause mutations if not handled properly.
   2. Radioactive fallout from nuclear plants — Nuclear reactors produce radioactive wastes from fuel and coolants. Leakage or improper disposal contaminates the environment.
   3. Nuclear weapons — Nuclear weapon tests release radioactive particles that are carried by wind and rain, polluting soil and water. These pollutants enter the food chain and ultimately affect human beings.
   4. Radioactive isotopes — Radioactive isotopes used in research laboratories may pollute rivers and lakes if discharged through wastewater.

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.

Answer

Yes, I agree that noise pollution is the most subtle form of pollution because it is often overlooked, yet it has many harmful effects.

Some of its harmful effects are:

1. Health hazards — It may cause stress, anxiety, hearing impairment, high blood pressure, and sleep disturbances.
2. Reduced efficiency — Excessive noise affects concentration, reduces productivity, and interferes with communication.
3. Mental discomfort — It causes annoyance, irritability, and disturbs peace of mind.
4. Impact on wildlife — It disturbs animals, affecting their communication, breeding, and natural behaviour.
5. Reduced quality of life — Continuous exposure to loud noise affects overall well-being and creates an unpleasant environment.

Pollution in the cities is the price of growing affluence. Give your views on the above statement with examples.

Answer

To a great extent, pollution in cities is the price of growing affluence because economic growth and urbanisation often lead to increased pollution.

Examples supporting this statement are:

1. Industrialisation — Rapid growth of industries releases smoke, harmful gases, and industrial wastes, causing air and water pollution.
2. Increase in vehicles — Higher incomes lead to more private vehicles, resulting in air and noise pollution.
3. Consumerism — Greater use of plastics, electronic goods, and other non-biodegradable products increases solid waste and environmental pollution.
4. Urbanisation — Rapid construction activities, increased energy consumption, and improper disposal of wastes contribute to air, water, soil, and noise pollution.

However, pollution is not an unavoidable price of development. Sustainable development, proper waste management, cleaner technologies, and strict pollution-control measures can reduce pollution while maintaining economic growth.