Voyage Solutions for ICSE Class 9 Geography Chapter 17 Sources Of Pollution

Exercises

I. Short Answer Questions

Question 1. Name any three air pollutants and the sources of each of them.
Answer: Common gaseous air contaminants and their primary release origins include:

Contaminants:
1. Carbon Monoxide (\( \text{CO} \))
2. Nitrogen Oxides (\( \text{NO}_x \))
3. Sulfur Oxides (\( \text{SO}_x \))

Release Origins:
1. Carbon Monoxide: Mainly produced by incomplete combustion of gasoline in vehicles, burning wood or coal, processing solid waste, and various industrial manufacturing plants.
2. Nitrogen Oxides: Primary contributors are tailpipe emissions from automobiles, electricity generating plants, burning of organic material, furnace vents, and waste incinerators.
3. Sulfur Oxides: Primarily generated through the combustion of sulfur-rich coal, metal smelting, petroleum refining, chemical processing, open garbage burning, and municipal waste combustion units.
In simple words: Three major air pollutants are carbon monoxide, nitrogen oxides, and sulfur oxides. They come from burning fuels like gasoline, coal, and wood in cars, factories, and power plants.

Exam Tip: When listing pollutants, use their chemical formulas alongside their names and match each pollutant directly to its major combustion source.

Question 2. What are natural sources of air pollution ?
Answer: Non-anthropogenic factors that contaminate the atmosphere include active volcanic discharges, blowing desert sand, airborne dust particles, and wild forest blazes.
In simple words: Nature can also pollute the air through volcano eruptions, blowing sand, dust storms, and wildfires.

Exam Tip: Ensure you distinguish between man-made and natural sources of pollution by using terms like "non-anthropogenic" or "natural phenomena."

Question 3. Name one industry which pollutes the atmosphere with gaseous as well as with particulate matter.
Answer: The vehicle manufacturing and assembly sector is a prime example of an industry that releases both hazardous exhaust gases and fine soot particles into the environment.
In simple words: The car industry is a major source of both toxic gases and tiny dust particles.

Exam Tip: The automotive sector (including manufacturing and vehicle operation) is the largest contributor to combined gaseous and particulate emissions.

Question 4. What is known as smog ? What harm is done by smog especially in winter ?
Answer: The term "smog" is a combination of atmospheric smoke and dense fog. During the colder winter months, this heavy mixture settles near the ground, severely reducing driving visibility and triggering numerous vehicular accidents.
In simple words: Smog is a mixture of smoke and fog. In winter, it makes the air very hazy, which blocks visibility and causes road accidents.

Exam Tip: Clearly define smog as the mixture of smoke and fog, and point to reduced visibility as the main reason for accidents in winter.

Question 5. Name three gases emitted during burning of garbage.
Answer: The combustion of household and municipal waste releases toxic gases such as carbon dioxide, sulfur dioxide, and various oxides of nitrogen.
In simple words: When trash is burned, it releases carbon dioxide, sulfur dioxide, and nitrogen oxides into the air.

Exam Tip: Remember that garbage contains organic and synthetic materials, which generate these three common acid-forming gases when burned.

Question 6. Mention any two sources of water pollution.
Answer: Two major pathways for aquatic contamination are:
* Household waste, including synthetic laundry soaps and domestic sewage.
* Accidental oil leakage from tankers or offshore drilling operations.
In simple words: Water gets polluted by soapy water and sewage from our homes, and by oil leaks in the ocean.

Exam Tip: Differentiate between point sources (like domestic sewage outfalls) and non-point/accidental sources (like oceanic oil spills).

Question 7. Name two heavy metals from industries that pollute water.
Answer: Two highly toxic industrial heavy metals that frequently contaminate water systems are mercury and lead.
In simple words: Lead and mercury are two toxic heavy metals released by factories that ruin water supplies.

Exam Tip: Mercury and lead are neurotoxins that accumulate in aquatic organisms, so they are highly critical to mention in exams.

Question 8. Mention any four sources of soil pollution.
Answer: Four primary causes of land contamination include:
1. Untreated industrial chemical discharges.
2. Municipal household trash and garbage.
3. Excessive agricultural application of chemical fertilizers.
4. Chemical bug-sprays and weed-killers (pesticides).
In simple words: Soil is polluted by factory chemicals, home garbage, farm fertilizers, and bug sprays.

Exam Tip: Present a balanced list containing both urban/domestic waste sources and agricultural chemical sources.

Question 9. Why are radioactive pollutants very dangerous ?
Answer: Radioactive isotopes, such as Uranium-235 and Plutonium-239, emit highly hazardous radiation following nuclear fission, turning entire regions radioactive. Because these fine particles are easily transported by winds across vast distances and have extremely long half-lives, they remain a severe, long-term threat to human health and safety.
In simple words: Radioactive materials like Uranium and Plutonium are extremely dangerous because they spread far with the wind and stay toxic in the environment for hundreds of years.

Exam Tip: Mention Uranium-235 and Plutonium-239 by name and explain their long-term persistence in the environment.

Question 10. What kind of solid and liquid pollutants does the offshore drilling produce ?
Answer: Deep-sea oil extraction operations generate solid debris, such as pulverized rock dust and stone fragments, along with liquid contaminants like crude oil leaks. These pollutants disperse across ocean waters, severely disrupting the delicate marine ecosystem.
In simple words: Drilling in the ocean produces solid waste like crushed rocks and stones, plus liquid oil spills that poison fish and sea plants.

Exam Tip: Categorize the answer clearly into solid waste (drill cuttings/stones) and liquid waste (crude oil spills).

Question 11. What are primary pollutants ?
Answer: Harmful agents released directly from their source into the environment that maintain their original chemical structure in the atmosphere are defined as primary pollutants. Typical examples include volcanic ash, radioactive isotopes, and direct oxides of nitrogen and sulfur.
In simple words: Primary pollutants are toxic chemicals let straight into the air exactly as they are made, like smoke ash and gases from exhaust pipes.

Exam Tip: The key defining phrase is "directly emitted from the source" in their original chemical state.

Question 12. With an example, state what are secondary pollutants?
Answer: These are harmful compounds that are not directly released from a source but are instead created through chemical reactions between primary pollutants and other atmospheric gases. Prominent examples include sulfur trioxide, ground-level ozone, ketones, and peroxyacetyl nitrate (PAN).
In simple words: Secondary pollutants are not made directly by factories; they form in the sky when other pollutants mix together, like ozone or PAN.

Exam Tip: Emphasize the chemical reaction between primary pollutants and normal atmospheric components, and use PAN or ozone as a key example.

Question 13. What is the connection between urbanisation and air pollution ?
Answer: The rapid expansion of city life drives up atmospheric pollution through the concentration of cars, industrial factories, municipal trash fires, and brick-making kilns. These urban activities discharge vast quantities of harmful substances, including oxides of nitrogen, sulfur, and carbon, along with hydrocarbons, ground-level ozone, and chlorofluorocarbons (CFCs).
In simple words: As cities grow, more cars, factories, and trash-burning sites are built. These release toxic gases that pollute the air we breathe.

Exam Tip: Link urban activities (vehicles, municipal waste, heating/industry) to specific chemical species (oxides of nitrogen/sulfur, hydrocarbons).

Question 14. How much are the automobiles responsible for air pollution ?
Answer: Motor vehicles are the single largest source of urban air contamination, accounting for approximately 80% of total emissions. They release massive amounts of carbon monoxide, unburnt hydrocarbons, and nitrogen monoxide.
In simple words: Cars and trucks are responsible for about 80% of air pollution in cities, releasing gases like carbon monoxide and hydrocarbons.

Exam Tip: Cite the exact figure of 80% and list carbon monoxide and hydrocarbons as the chief vehicular exhaust gases.

Question 15. How are brick kilns a source of gases and particulate matter that cause air pollution ?
Answer: The high-temperature firing processes in brick-making furnaces release immense quantities of gaseous carbon oxides, along with soot, heavy smoke, and particulate dust into the air.
In simple words: Brick-making ovens burn a lot of fuel, which produces thick smoke, dust, and carbon gases.

Exam Tip: Highlight that brick kilns release a combination of gases (carbon oxides) and physical solids (particulate matter/soot).

II. Long Answer Questions

Question 1. With reference to noise pollution, answer the following:
1. How does traffic contribute to noise pollution ?
2. Why are the construction sites considered as worse than factories in their contribution to noise pollution ?
3. How do the airplanes cause noise pollution ?
Answer: 1. Traffic Noise: The continuous growth of vehicle numbers on roads represents a massive source of acoustic disturbance. In crowded city centers, frequent traffic gridlocks prompt frustrated drivers to blare their horns repeatedly, generating high levels of ambient noise.

2. Construction Sites vs. Factories: Demolition and building zones are often more disruptive than established manufacturing plants. Factories generally operate within enclosed walls with localized sounds, whereas outdoor building projects involve heavy, unshielded machinery - such as jackhammers, drills, and concrete mixers - operating in open air at extremely high decibels.

3. Aviation Noise: Noise from aircraft has grown continuously due to the high volume of heavy, long-range commercial jet travel. Jet engines generate highly disturbing, high-pitched noise caused by the turbulent mixing of hot exhaust gases with cooler surrounding air. This sound peaks during takeoff when engines are at full throttle. During landings, planes fly low to the ground for miles, emitting a persistent, high-frequency whine from spinning engine compressors and turbines that acts as a continuous environmental nuisance.
In simple words: 1. More cars on the road and constant horn-honking cause heavy traffic noise. 2. Construction sites are louder than factories because they use heavy, unshielded machines outdoors. 3. Jet airplanes create a loud whine when they take off and land near neighborhoods.

Exam Tip: In part 3, distinguish between takeoff noise (mixing of exhaust gases with air) and landing noise (air compressor and turbine blade hum).

Question 2. Air pollution is the contamination of air by pollutants. In this context answer the following :
(i) How does the use of automobiles cause air pollution ?
(ii) Write short notes on industrial air pollution.
(iii) What special kind of air pollution do the brick kilns produce?
Answer: (i) Vehicular Emissions: Motor vehicles pollute the atmosphere by releasing vast quantities of carbon monoxide, unburnt fuel hydrocarbons, nitrogen oxides, and fine suspended dust particles.

(ii) Industrial Air Pollution: While factory operations are essential for economic growth, they present a major environmental hazard in urban zones. Industrial processes burn fossil fuels and release chemical emissions, sending pollutants like carbon monoxide, sulfur dioxide, nitrogen oxides, thick smoke, and heavy fly ash into the atmosphere.

(iii) Brick Kiln Pollution: Brick-making operations are notorious for releasing dense black smoke and large volumes of physical dust particles (particulate matter) that degrade local air quality.
In simple words: (i) Cars release gases like carbon monoxide and tiny soot particles. (ii) Factories help us develop but release toxic sulfur, nitrogen, and carbon gases into urban areas. (iii) Brick kilns produce thick smoke and a lot of dust.

Exam Tip: Ensure you list the specific chemical species emitted (such as CO, \( \text{SO}_x \), and hydrocarbons) in each part of the answer.

Question 3. With reference to the sources of water pollutants answer the following questions:
(i) Why is it harmful to dispose of household detergents in water bodies ?
(ii) In what way does the industrial waste pollute water?
(iii) How do the radioactive wastes get into the water bodies?
(iv) How is the thermal pollution of water caused ? What are its effects ?
Answer: (i) Household Detergents: Synthetic laundry soaps contain high levels of phosphate compounds. When washed into streams and lakes, these phosphates fertilize the water, triggering massive algal blooms and dense weed growth that deplete oxygen and choke out marine life.

(ii) Industrial Effluents: Chemical factories and manufacturing plants produce highly toxic liquid waste. A notable example is the leather tanning cluster in Kanpur, which continuously discharges harmful chemical waste into the Ganges River. These chemical mixtures make natural waters poisonous, spread pathogens, and lead to serious waterborne diseases.

(iii) Radioactive Infiltration: Radioactive isotopes enter municipal water systems via liquid wastes discharged from nuclear power reactors, military weapons tests, scientific research labs, and medical cancer-treatment centers.

(iv) Thermal Pollution: Industrial power plants use large volumes of river water to cool down heavy machinery. This water absorbs heat and is subsequently discharged back into the river at elevated temperatures. This sudden temperature hike reduces the water's ability to hold dissolved oxygen, suffocating fish and disrupting the entire aquatic ecosystem.
In simple words: (i) Laundry soaps contain phosphates that act like plant food, causing weeds and algae to take over water bodies and suffocate fish. (ii) Factories dump poisonous chemical waste into rivers (like the tanneries in Kanpur), which ruins clean water and spreads illnesses. (iii) Radioactive waste gets into water from nuclear plants, hospital research, and weapon testing. (iv) Power plants use river water to cool their machines and dump the hot water back. This warm water holds less oxygen, which is dangerous for fish.

Exam Tip: For thermal pollution, connect "increased water temperature" directly to "decreased dissolved oxygen solubility" to explain why aquatic life suffocates.

Question 4. Write short notes on soil pollution by
(a) Pesticides
(b) Biomedical waste.
Answer: (a) Soil Contamination by Pesticides: Chemical sprays and weed-killers applied to crops accumulate in the soil, altering its natural nutrient balance and killing beneficial soil microbes. These toxic chemicals can be absorbed by plants, poisoning the food chain. Because these compounds do not break down easily, they cause long-term soil toxicity.

(b) Soil Contamination by Biomedical Waste: Hospital waste contains dangerous biological matter, discarded syringes, sharp metal implements, toxic medicines, and synthetic plastics. When dumped in landfills, these items leach toxic chemicals into the ground, rendering the soil completely barren and creating biohazards. This is a severe problem in developing nations lacking proper waste-treatment facilities.
In simple words: (a) Pesticides sprayed on crops poison the soil for years and get absorbed by the food we eat. (b) Hospital waste like plastics, needles, and chemicals poisons the ground, making it barren and spreading diseases.

Exam Tip: Note that pesticides are persistent organic pollutants (POPs) that cause long-term damage, while biomedical waste presents both chemical and biological biohazards.

Question 5. What are the sources of radioactive pollution ? Describe each of them.
Answer: The sources of radioactive contamination are categorized as:

Natural Sources:
* Cosmic Radiation: Outer space continuously sends high-energy rays that penetrate Earth's atmosphere.
* Earth minerals: Natural elements like radon and uranium present in the crust emit low-grade background radiation.

Anthropogenic (Man-made) Sources:
* Diagnostic Imaging: The widespread use of medical X-rays and imaging equipment.
* Military Activity: Detonations and testing of nuclear weapons.
* Nuclear Power: Atomic energy reactors and spent fuel rods.
* Scientific Research: The disposal of radioactive chemical isotopes from research labs and hospital facilities into public sewer systems.
In simple words: Radioactive pollution comes from natural sources like cosmic rays from space, and man-made sources like hospital X-rays, nuclear reactors, and weapons testing.

Exam Tip: Classify your answer clearly into "Natural Sources" and "Man-made Sources" for better structure and grading.

Question 6. What are the man-made sources of air pollution ?
Answer: Human-induced sources of atmospheric degradation stem directly from modern activities, including:
1. Manufacturing factories and heavy chemical industries.
2. Concentrated urban residential areas (burning fossil fuels for heat and cooking).
3. Exhaust emissions from motor vehicles, commercial aviation, and shipping.
4. Explosions from nuclear weapons testing.
5. Dust and chemical sprays from agricultural farming.
6. Power plants burning coal to generate electricity.
In simple words: Human activities like driving cars, running factories, heating city homes, farming, and running coal power stations pollute our air.

Exam Tip: Provide a diverse list covering industrial, domestic, agricultural, and transportation-related sources.