Question 1

Question 2State the causes of soil pollution.

Accepted Answer

The causes soil pollution are deposition of solid waste, accumulation of non-biodegradable material and toxic chemicals etc., which come from the following sources:Industrial waste — Industrial waste containing chemicals, when dumped in soil, cause soil pollution. For example, fly ash from thermal plants, chemicals from oil refineries pollute the soil.Urban commercial and domestic waste — Non-biodegradable wastes like glass, plastic, polythene bags remain in the soil for a long time.Chemical fertilizers — Chemical fertilizers when used, disturb the natural balance of the soil. They also contaminate water bodies through run-off.Biomedical waste — Hospital wastes containing plastics, metal needles and chemicals are dumped in soil.Pesticides — Pesticides show permanent accumulation in soil in the form of nitrates and phosphates.

Question 2

Question 3State the effects of freshwater pollution. How is it caused?

Accepted Answer

The effects of freshwater pollution are:Eutrophication and death of aquatic animals — Nitrate and phosphate accumulate in water bodies with run off water. They may be derived from fertilizers and detergents. They overstimulate the growth of aquatic plants and algae, resulting in eutrophication.Disturbance in aquatic ecosystem — Leached heavy metal and chemicals may kill aquatic animals and plants disturbing the aquatic ecosystem.Oil spill results in a layer of oil over the water surface, insulating the water from the atmosphere. This lowers the level of dissolved oxygen in water and ultimately leads to loss of aquatic life.Many industries dump hot water in the freshwater bodies which raises the temperature of water and causes adverse effects on the aquatic creatures.Freshwater pollution is caused due to:Natural sources — The natural sources are gases, animal waste, living organisms, soil, minerals (Nickel, Cobalt, Lead and Mercury etc.) and other pollutants soluble in water.Human sources — Urbanization and industrialization have resulted in excessive water pollution. The human sources of water pollution can be classified as follows:Sewage and Domestic wasteIndustrial wasteAgricultural wasteNuclear wasteOil spillsThermal pollution

Question 3

Question 4How do agricultural wastes harm the environment?

Accepted Answer

Agricultural wastes harm the environment in the following way:Agriculture, including commercial livestock and poultry farming is a source of many organic and inorganic pollutants in surface waters. Pesticides from agricultural run off, metals and processed chemicals are also major sources of water pollutants.Excess nitrates and phosphates lead to Eutrophication in water bodies which leads to loss of aquatic life and disturbs the aquatic ecosystem.Chemical fertilizers and pesticides contain potassium and phosphorus, which are released in water bodies through run-off water. This also affects the plant growth in the soil.Radio-tracers extensively used in agriculture are also responsible for radiation pollution.

Question 4

Question 5Which gases are emitted through refrigerators and air-conditioners?

Accepted Answer

Chlorofluorocarbons are the gases emitted through refrigerators and air-conditioners.

Question 5

Question 6Differentiate between the natural and man-made sources of pollution.

Accepted Answer

S.No.Natural sources of pollutionMan-made sources of pollution.1.The sources of pollution that emit pollutants naturally.Pollutants are released due to human activities.2.Example - volcanic eruption, forest firesExample - burning of fossil fuels, automobile fumes, deforestation etc.3.Not under our control.Can be avoided with careful planning.

Question 6

Question 7What is meant by oil spill?

Accepted Answer

The leakage or spill of oil in the sea causes a layer of oil spreading on the surface of water. This is known as oil spill. The oil spread on the sea water acts as an insulating layer between air and water. Due to this, the oxygen of the atmosphere cannot mix with water and causes death of aquatic creatures.

Question 7

Question 8How is oil spill caused?

Accepted Answer

Oil spill may be caused in the following ways:waste oil from city drains, tankersleakage from oil wellaccidental oil spill

Question 8

Question 9What is meant by radiation?

Accepted Answer

The emission of highly charged particles and electro-magnetic rays from radioactive substances is called radiation.

Question 9

Question 10Explain the following terms :(a) Smog(b) Pollutants(c) CFC(d) Eutrophication

Accepted Answer

(a) Smog — The term 'smog' is derived from 'smoke + fog' as it is formed due to mixing of smoke and fog. Smog is common in industrial areas in winters. It reduces visibility and is unhealthy for humans, animals and plants.(b) Pollutants — The substances or materials that cause pollution are called pollutants. They are harmful for the environment and living beings. They can be natural such as volcanic ash or man-made like plastic.(c) CFC — CFC or Chlorofluorocarbons are the synthetic chemical compounds which are used as refrigerant or cooling agent in AC and refrigerators. When these chemicals are released in atmosphere, they split due to ultraviolet rays and damage the ozone layer.(d) Eutrophication — The process by which the excess phosphates and nitrates lead to over growth of algae and other aquatic plants in a water body, depleting the oxygen of water, is called Eutrophication.

Question 10

Question 11Write a short note on the following:(a) Radiation(b) Oil spill(c) Air pollution(d) Noise pollution

Accepted Answer

(a) Radiation — Radiation pollution is the emission of highly charged particles and electromagnetic rays entering the earth's atmosphere. Sources of radiation may be natural or man-made. Natural sources consist of cosmic rays that pollute the life supporting systems like air, water and soil. Man-made sources consist of waste water from nuclear power stations, mining of uranium ore, waste from hospitals where isotopes are used for diagnostic and therapeutic purposes etc.(b) Oil spill — The leakage or spill of oil in the sea cause a layer of oil spreading on the water. This is known as oil spill. The oil spread on the sea water acts as an insulating layer between air and water. Due to this, the oxygen of the atmosphere cannot mix with water. It leads to death of aquatic animals due to deficiency of dissolved oxygen. The birds cannot fly as their feathers are oil-soaked.(c) Air pollution — The contamination of air with harmful gases and particles is called air pollution. Natural sources of air pollution consist of volcanic eruption, dust storms and forest fires. Man-made sources consist of burning of fossil fuels, use of CFCs, industrial and construction wastes etc. Air pollution leads to poor air quality which further result in breathing problems, lung diseases, smog, damage to buildings and also disrupts ecological balance.(d) Noise pollution — Any sound that causes annoyance is regarded as noise and is considered as a source of pollution. Sound level of about 80 decibels causes noise pollution. The sources of noise pollution are aeroplanes,trains, loud-speakers, fire crackers and industries etc. Noise pollution cause discomfort, deafness, high blood pressure, palpitation, headache etc.

Question 11

Question 12What kind of pollution is produced by brick kilns?

Accepted Answer

Brick Kilns cause air pollution. They use coal to burn the bricks. They give out huge quantity of carbon dioxide and particulate matter such as smoke, dust which is very harmful. Brick kilns cause air pollution.

Question 12

Question 13How is thermal pollution caused?

Accepted Answer

The thermal power plants release the recycled hot water into the rivers and sea causing water pollution. The hot water raises the temperature of the water body. It can lead to a decrease in the dissolved oxygen level in the water while also increasing the biological demand of aquatic organisms for oxygen.

Question 13

Question 14What are the sources of radioactive pollution?

Accepted Answer

The sources of radioactive pollution are:Natural sources — Cosmic rays emit radioactive radiation.Man-made sources — waste water from nuclear power plant, waste generated during nuclear weapon testing, mining and processing of uranium ore, waste generated from hospitals and research laboratories where radioisotopes are used, X-ray waste, nuclear accidents, nuclear bomb explosions and use of radio tracers.

Question 14

Question 15How do water bodies get contaminated by the effluents from industries?

Accepted Answer

Water bodies get contaminated by the effluents from industries in following ways:Waste and sewage generated by industry can get into the water supply, introducing large organic pollutants into the ecosystem.Most of the industries release chemicals like chlorides, sulphides, carbonates, nitrates and metal like Zinc, Mercury, Copper, Chromium, etc. in the rivers or their water sources.Water can become contaminated with toxic or radioactive material from the industry, mine sites and abandoned hazardous waste sites.Air pollution leads to acid precipitation which lower the overall pH of lakes, streams, and ponds; thereby killing vital plants and affecting the whole food chain.Leaching of heavy metals from soil into the water bodies leads to contamination of water. It may kill aquatic flora and fauna.

Question 15

Question 16What is the difference between primary and secondary pollutants?

Accepted Answer

S.no.Primary pollutantsSecondary pollutants1.They are directly released into the air.They are formed due to chemical interactions between the atmospheric components and primary pollutants.2.For example- smoke, dust, ash, sulphur oxide, nitrogen oxide etc.For example- smog, acid rain.3.It is comparatively less harmful.It is more harmful.

Question 16

Question 17How does urbanization cause air pollution?

Accepted Answer

Urbanization has resulted in concentration of industries around the cities. Big and small industries, power plants, brick kilns create air pollution. Also there are numerous vehicles in the urban areas creating a lot of air pollution. Urbanization causes air pollution in following ways:The burning of fuels in automobiles and aeroplanes lead to emission of Carbon Monoxide and Hydrocarbons containing nitrogen and oxygen.Industries like il refinery discharge Ammonia, Hydrocarbons and Sulphur oxide. Aluminium plants release fluoride dust.Burning of garbage lead to emission of carbon dioxide and nitrogen oxide.Brick kilns also release huge quantity of Carbon dioxide and particulate matters.Use of cleansing agents release chemicals like Ammonia and chlorine, causing indoor pollution.Use of radioactive elements or use of isotopes(medical purpose) lead to emission of α, β and γ radiations.

Question 17

Question 1As per the report of National Oceanic and Atmospheric organization Sixty-five percent of the estuaries and coastal waters in the contiguous U.S. that have been studied by researchers are moderately to severely degraded by excessive nutrient inputs. Excessive nutrients lead to the growth of many algae in turns death of many fish.Identify the process.Why is the concentration of excessive nutrients responsible for the death of aquatic animal?

Accepted Answer

The process is called Eutrophication.When excessive nutrients, such as nitrogen and phosphorus, enter water bodies, they promote rapid algae growth. This overgrowth blocks sunlight and, when the algae die and decompose, the process uses up large amounts of dissolved oxygen in the water. The resulting drop in oxygen levels, known as hypoxia, makes it difficult for fish and other aquatic animals to survive, leading to their death.

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