Question 1

Question 1Given below are scenes, list the main pollutants for each and identify which type of pollution each causes. Give reasons to support your answers.Picture APicture B

Accepted Answer

(a) The main pollutants in Picture A are —Carbon monoxide (CO)Unburnt hydrocarbonsNitrogen monoxide.These pollutants contribute to Vehicular Air Pollution, primarily affecting air quality and human health.Reasons —These pollutants are emitted from the incomplete combustion of fuel in automobile engines, which is a major cause of air pollution.Carbon monoxide is a toxic gas that reduces the oxygen-carrying capacity of the blood.Unburned hydrocarbons such as methane, acetylene, and ethylene are volatile and contribute to smog formation.Ethylene, in particular, undergoes chemical reactions in the presence of sunlight and nitrogen oxides (NOₓ) to form photochemical oxidants, such as ozone, which are harmful to health and the environment.Nitrogen monoxide (NO), released during fuel combustion, reacts with oxygen to form nitrogen dioxide (NO₂), which is another harmful pollutant.(b) The main pollutants in picture B are —SmokeParticulate matter (dust)Sulphur dioxide (SO₂)Nitrogen oxides (NOₓ)Carbon monoxide (CO)These pollutants are responsible for causing Air Pollution.Reasons —During the production of building materials, large quantities of dust and fine particulate matter are released into the air, especially from processes like crushing, grinding, and heating raw materials.The smoke coming out from the factories producing contruction materials has small particles of dust, carbon, metals, other solids, liquids and radioactive materials which get mixed in smoke and pollute the air.The combustion of fossil fuels to power machinery and kilns emits sulphur dioxide, nitrogen oxides, and carbon monoxide into the atmosphere.These pollutants reduce air quality, cause respiratory problems, and contribute to smog and acid rain.

Question 2

Question 5Mention any two sources of water pollution.

Accepted Answer

Two sources of water pollution are-Domestic sources, like phosphates from detergents and fertilisers.Industrial sources, like heavy metals and synthetic organic compounds.

Question 3

Question 8Why radioactive pollutants are very dangerous?

Accepted Answer

Radioactive pollutants are very dangerous because of the following reasons-Radioactive wastes from atomic reactors are hazardous to living organisms.Even if radioactive wastes are buried underground, they may escape into the surroundings.Inert gases escape as vapours and pollute the environment.The radioactive wastes emitted during the testing of nuclear weapons makes the surrounding materials radioactive.Radioactive materials are carried away to distant places by winds. They are brought down by rain. Raindrops containing these radioactive particles fall on earth,and affect the soil causing soil pollution.The radioactive materials in the soil reach water sources, where the aquatic organisms absorb and accumulate them through the food chains and pass them on to human beings.

Question 4

Question 10How does lighting of crackers cause pollution?

Accepted Answer

Lighting of crackers significantly contributes to Air Pollution and Noise pollution.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.Noise Pollution: Loud explosions from crackers exceed safe decibel levels, causing hearing discomfort, stress, and disturbance to humans and animals.

Question 5

Question 1(c)With reference to noise pollution, answer the following:Why are the construction sites considered as worse than factories in their contribution to noise pollution?

Accepted Answer

The construction sites are considered as worse than factories in their contribution to noise pollution because whatever construction takes place noise emissions levels are higher as well as the equipment is inherently noisy.In the era of fast urbanisation the demolition and the repair activities along with the huge machines used for the purposes create a great deal of noise to the annoyance of the people living near the sites of construction.

Question 6

Question 1(d)With reference to noise pollution, answer the following:How do the airplanes cause noise pollution? Why is there more noise pollution during landing as compared to during take-off?

Accepted Answer

The airplanes cause noise pollution as the noise made by the jet planes is more disturbing than that of the old propeller driven aircraft because it is of far higher pitch. Jet noise is caused by the violent mixing of the jet of gases from the engine with the surrounding air. It is at maximum level during take-off when the engine delivers maximum thrust, and reduces rapidly as the aircraft climbs.During landing, the main source of high-frequency noise is the sound made by the air compressor and turbine blades. Air crafts pass close to the ground for quite a distance during landing operation and this noise often constitutes a more sustained environmental nuisance than the intense noise of shorter duration produced during take-off. Hence, there is more noise pollution during landing as compared to during take-off.

Question 7

Question 2(b)Air pollution is the contamination of air by pollutants. In this context answer the following:How does the use of automobiles cause air pollution?

Accepted Answer

Vehicles are mainly responsible for more than 80% of total air pollution. The major pollutants released from automobiles, locomotives, aircraft etc., include carbon monoxide, unburnt hydrocarbons and nitrogen monoxide. In the major metropolitan cities like Delhi, Mumbai and Kolkata, vehicular exhaust accounts for 75% of all CO, 45% of all hydrocarbons, 40% of all oxides and 30% of all suspended particulate matter.Air pollution is also caused by the gaseous and volatile hydrocarbons such as methane, acetylene and ethylene. Some hydrocarbons like ethylene, which undergo chemical reactions in the presence of sunlight and nitrogen oxide form photochemical oxidants that are harmful. Fuel combustion in automobiles also produces nitrogen dioxide.

Question 8

Question 2(c)Air pollution is the contamination of air by pollutants. In this context answer the following:How do industries pollute the air?

Accepted Answer

Industries such as chemical industries, paper and pulp mills, cotton mills and petroleum refineries produce most air pollution. The cement factories emit dust, which is potential health hazard. The smoke coming out from the factories has small particles of dust, carbon, metals, other solids, liquids and radioactive materials which get mixed in smoke and pollute the air.The burning of sulphur in coal or heavy oil in thermal power plants releases sulphur dioxide in the air. Sulphur dioxide combines with oxygen and water to form sulphuric acid in the atmosphere which is a health hazard. Besides, it produces acid rain.

Question 9

Question 3(a)With reference to the sources of water pollutants answer the following questions:What are the domestic sources of water pollution?

Accepted Answer

Man uses water for drinking, preparation of food, bathing, for cleaning the house, etc. Most of the used water is drained out through municipal drains and poured into a river or lake. Domestic waste water that is mixed with other wastes such as plastic, detergents, animal dung and human faecal material is known as municipal waste.Many detergents and fertilisers 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.

Question 10

Question 3(c)With reference to the sources of water pollutants answer the following questions:In what way does the industrial waste pollute water?

Accepted Answer

Industries dealing with chemicals, pulp and paper, food processing, etc. produce waste material such as heavy metals or synthetic organic compounds. These reach water bodies either through direct discharge or by leaching from waste dumps. Among the heavy metals, cadmium, lead, mercury, copper, chromium etc., get into water.The industrial waste mixed with water makes it poisonous and unhygienic. It may also cause various diseases in humans and animals, if consumed without treatment.

Question 11

Question 3(d)With reference to the sources of water pollutants answer the following questions:What are the sources of radioactive pollution? Describe each of them.

Accepted Answer

The two main sources of radioactive pollution are-Natural sources — These sources are cosmic rays with energetic radiations reaching the earth from outer space. Though they are a major hazard in space, they are not dangerous for organisms on earth.Man made sources — The following sources cause radioactive pollution-X-rays waste — The use of X-rays is common for detecting skeletal disorders. Cancer patients undergo radium and other isotope radiations. The X-rays pass through genetic cells and affect the chromosomes, resulting in mutations.Radioactive fallout from nuclear plants — In a nuclear power establishment, both fuel elements and coolants are sources of radiation pollution. Radioactive wastes from atomic reactors are hazardous to living organisms. Even if radioactive wastes are buried underground they may escape into the surroundings. Inert gases escape as vapours and pollute the environment.Nuclear weapons — Testing of nuclear weapons involves using radioactive substances like Uranium 235 and Plutonium 239 for fission. The radioactive waste emitted during these tests makes the surrounding materials radioactive. Radioactive particles are carried away to distant places by wind. They are brought down by rain. Raindrops containing these radioactive particles fall on earth and affect the soil causing pollution. From the soil, the radioactive materials reach water sources, where the aquatic organisms absorb and accumulate them through the food chains and pass them on to human beings.Radioactive isotopes — Radioactive isotopes are used in research laboratories. When the waste water from these laboratories reaches the rivers, streams, lakes etc., through the sewers they cause water pollution.

Question 12

Question 2Pollution in the cities is the price of growing affluence. Give your views on the above statement with examples.

Accepted Answer

The statement "Pollution in the cities is the price of growing affluence" reflects a commonly observed phenomenon in urban areas. Some examples to support the statement are as follows:Industrialization and economic growth — Rapidly developing cities in emerging economies like India have faced severe air pollution issues due to the growth of industries and an increase in vehicular traffic.Energy consumption and urbanisation — With affluence comes higher energy consumption and urbanisation, leading to increased pollution. Cities with high levels of affluence and urbanisation such as New York City and Tokyo, have faced challenges related to air pollution, waste management, and water pollution due to the concentration of human activities.Lifestyle choices and consumerism — Disposable plastic products, including single-use plastic bags and packaging, are commonly used in affluent societies, contributing to plastic pollution in cities and the environment.

Sources of Pollution

Classification Of Pollutants

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