Environmental Chemistry Terminal Questions with Answer NIOS

Environmental Chemistry Terminal Questions with Answer NIOS National Institute of Open Schooling | NIOS

Environmental Chemistry Terminal Questions with Answer NIOS

National Institute of Open Schooling (NIOS)
Sr. Secondary, Module-8
Lession-32: Environmental Chemistry Terminal Questions with Answer NIOS


1. What is environment?

The word Environment is derived from the French word Environ which meaning surrounding. The environment can be stated as a system encompassing all biotic and abiotic elements affecting human life.

2. Explain the term anthropogenic pollutants.

Pollution due to human activities is called anthropogenic pollution. Anthropogenic pollutants are of two kinds-
A. Primary pollutants: It is added directly in a harmful form to the atmosphere.
B. Secondary Pollutants: It is the products of the reaction between the primary pollutants and normal environmental constituents.
Depending on sources anthropogenic pollutants divided into two types-
A. Industrial Pollutants: Paper, textile industries, tanneries, and distilleries dispose of various effluents like oil, grease, plastic, and metallic wastes into the environment.
B. Domestic Pollutants: Detergents, fluoride toothpaste, food flavoring agents, polythene bags, and wrappers find their way into the environment as pollutants. Methane is produced in cattle stomachs and stagnant paddy fields is also a domestic pollutant.

3. Write four major pollutants of water, their sources and effects.

Water pollution occurs when harmful substances—often chemicals or microorganisms—contaminate a stream, river, lake, ocean, aquifer, or other body of water, degrading water quality and rendering it toxic to humans or the environment.
Four major pollutants of water are-
1. Pesticides and insecticides
2. PLastics
3. Chlorine compounds
4. Lead
Sources and Effects
1. Pesticides and insecticides: Sources of it is improper to use in agriculture, mosquitos repellants. Its effect is Toxic to fishes, predatory birds, and mammals.
2. Plastics: Source of plastics are Homes and industries. It Kills fishes and animals like cows.
3. Chlorine compounds: Sources are Water disinfection with chlorine, paper, and bleaching powder. It affects on fatal for plankton (organisms floating on the surface of industries water) foul taste and odour, can cause cancer in humans.
4. Lead: The sources of lead are Leaded gasoline, paints, etc. Lead can damage the kidney, liver, reproductive system, etc.

4. Differentiate between the Primary and Secondary Pollutants.

Pollutants that enter directly from the sources into the atmosphere are called primary pollutants e.g. carbon dioxide and carbon monooxide from the burning of fossil fuel, sulphur dioxide and oxides of nitrogen from vehicular combustion, thermal power stations, etc. However, Pollutants that are formed due to interactions between primary air pollutants and other atmospheric components are called secondary pollutants. These interactions can be physical or chemical. Acid rain, Photochemical smog, Peroxyacetyl nitrate(PAN) etc. are the examples of secondary pollutants. Secondary pollutants are more harmful than primary pollutants.

5. What are the damaging effects of SO2 and NO2 on plants and animals?

SO2 can cause bronchitis and lung cancer on exposure to higher levels. SO2 causes excessive water loss in plants. This air pollutant decreases the quality of plants and affects plant yield. It reduces crop yields. Elderly people and children are more prone to having asthma on exposure for a long duration.
Oxides of nitrogen can increase the chances of acute respiratory illness such as acute bronchitis in children. It can also increase airway resistance in adults. It causes early fall of leaves and fruits in plants.

6. Write a note on carbon monoxide poisoning.

Carbon Monoxide Poisoning can result in brain damage and even death. As carbon monoxide is a colorless and odorless gas we can't see, smell, or taste it, but it can be fatal for human beings. Carbon monoxide has a great affinity for Haemoglobin(Hb). Carbon monoxide combine with Hb to form CO-Hb and reduces the amount of oxygen supply to brain due to it combines about 200 times faster than oxygen. CO poisining victim have dark red lips.

7. What is thermal inversion and how is it caused?

Thermal inversion is a natural phenomenon that involves a change in the normal tendency of the air to cool down with altitude and that runs as follows: During the night, the earth's surface cools quickly, transmitting that cold to the atmosphere closest to the ground. This layer of air has a lower temperature than the immediately higher one, that is, both have different densities, which prevents mixing. The thermal inversion is usually corrected as the sun reheats the earth's surface, restoring normal operating conditions.

8. Enumerate the various effects of acid rain.

Some of the effects of acid rain are listed below-
1. Excessive acid concentrations are phytotoxic (toxic to plants). There have been widespread death of trees in forests due to acid rain.
2. Sea waters are rich in minerals and have great buffering capacity. But buffering capacity of fresh water bodies is low and acid deposits have a toxic effect on the fresh water ecosystems.
3. Mature (capable of reproduction) fish survives in acid rain fed water bodies but fails to reproduce. So there are no young fish in such waters.
4. Exposed surfaces of buildings, statues get corroded. Limestone or marble (CaCO3) structures are specially damaged. The chemical reaction is like-
CaCO3 + H2SO4 → CaSO4 + CO2 + H2O.
The sulphates are leached out by rain water.
5. Acidic sulphate when present in the atmosphere causes laziness. Acidic mist falling on the ground reduces visibility.

9. What is ozone hole? What are the effects of ozone depletion?

Ozone holes refer to the depletion of ozone molecules in the ozone layer due to the reaction of Chloro fluorocarbons (CFCs). The holes in the ozone layer appear elsewhere and not where these chemicals are used.
Effects of ozone depletion are- Increased embryonic mortality in animals and humans. It increases in certain types of skin cancer, cataracts of the eyes, and disorders with immune deficiency. UV rays affect plant growth, flowering and photosynthesis so it reduces farm productivity.

10. Why does sea level rise due to global warming?

Sea level rise due to global warming, because of Global warming increase in the earth's temperature. Polar ice caps would melt because of temperature rise and add more water to the sea. Moreover, water expands when it heats up. This will lead to a rise in sea level. It will flood the low lying coastal area and many cities will get submerged in water.

11. How do greenhouse gases cause global warming.

Global warming is the gradual increase in the average temperature of the earth's atmosphere. It is caused by the increased concentration of greenhouse gases in the atmosphere due to various human activities like the burning of fossil fuels, large-scale deforestation, etc.
The greenhouse gases like carbon dioxide, methane, and others trap the heat coming from the sun in the atmosphere and prevent it from escaping. This phenomenon is called the greenhouse effect. It makes the surface of the earth warm and makes the survival of living beings possible. However, due to the increased concentration of greenhouse gases, the temperature of the earth has increased considerably leading to global warming.

12. Mention five disease/discomforts in humans caused by different air pollutants.

Diseases caused by air pollutants are-
Emphysema, Bronchitis caused by CO, SO2, PAN, O3
Eye irritation, headache caused by SO2, PAN, O3
Silicosis, Asbestosis caused by Suspended particulate matter like silica, asbestos
Coronary artery disease caused by Tobacco smoke
Anemia, kidney, liver damage caused by Pb
Fluorosis, Skin Cancer caused by Fluorides
Poisoning death caused by CO

13. Enumerate the various measures of control of air pollution.

Measures of control of air pollution are-
1. Proper treatment of industrial gaseous waste: The gaseous wastes should be treated in a cyclone collector or electrostatic precipitator prior to disposal.
2. Segregated localization of industrial plants: Industrial plants should be located in areas far from human settlements and be surrounded by sufficient greenery to compensate for the pollution caused by them.
3. Usage of green fuel: Green fuel refers to biodegradable fuel derived from natural gas that can be used to replace petroleum and diesel. 4. Installation of scrubbers: Installing scrubbers in the engines of cars will sequester the oxides of sulfur and nitrogen. Thus, they will not be released into the environment.
5. Reducing the burning of coal: This will lower the concentration of unburnt hydrocarbons released in the air.

14. How the industrial wastes and domestic wastes are helpful in soil pollution?

Industrial wastes are the major cause of soil pollution because the wastes are toxic due to the presence of cyanides, chromates, acids, alkalies, metals like nickel, cadmium, mercury, and lead. The urban and domestic wastes are referred to as soil refuse, containing garbage, and rubbish, paper pieces, glass, plastics polythene bags, cans detergents, and cakes. These substances emit gases, toxic hydrocarbons, and pathogenic microbes cause disease.

15. What are fungicides.

Fungicide is a specific type of pesticide that controls fungal disease by specifically inhibiting or killing the fungus causing the disease.

16. How to control soil pollution?

The following steps have been suggested to control the soil pollutioins-
i. The use of chemical fertilizers can be reduced by applying bio-fertilizers and manures.
ii. Recycling and recovery of materials appears to be a reasonable solution for reducing soil pollutions. Materials like papers, gas and some kinds of plastics can be recycled.
iii. Control of land loss can be attempted through restoring forests and grass cover to check soil erosion and flood.
iv. Proper methods should be adopted for the disposal of solid wastes.

17. Explain main effects of water pollutions.

The effects of water pollution are given below -
i. Water pollution brings about a dangerous effect on human health as well as on the ecosystem.
ii. Water pollution contaminates the water making it unsafe for drinking and due to which many waterborne diseases take place.
iii. Water pollution causes eutrophication which causes fish and other aquatic animals to die.
iv. As the aquatic animals are affected by the water pollution it can also make a way to humans through the aquatic organisms.
v. Due to water pollution it leaches chemicals into the soil that impact the growth of plants and food crops.

18. What are the various types of water pollutants? State their consequences.

various types of water pollutants are-
A. Sewage Pollutants (Domestic and Municipal Waste)
B. Industrial Pollutants
C. Agricultural Pollutants
D. Physical Pollutants
E. Petroleum Products
A. Sewage Pollutants (Domestic and Municipal Waste): The sewage contains garbage, soaps, detergents, waste food and human excreta and is the single largest sources of water pollution. Pathogenic (disease causing) microogranisms (baccteria, fungi, protozoa, algae) enter the water system through sewage making it infected.
Typhoid, chloera, gastroenteritis and dysentery are commonly caused by drinking infected water.
Water polluted by sewage may carry certain other bacteria and viruses cannot grow by themselves, but reproduce in the cells of host organisms. They cause a number of diseases, such as polio, viral hepatitis and may be cancer which are resistant to like the organic matter are oxygen demanding substances. They are responsible for deoxygenation of water-bodies which is harmful for aquatic life.
Other ingedients which enter the various water bodies are the plant nutrients i.e., nitrates and phosphates. They support growth of algae, commonly called algal bloom (blue-green species). This process is called eutrophication.
B. Industrial Pollutants: Many industries are located near rivers or fresh water streams. These are responsible for discharging their untreated effluents into rivers like highly toxic heavy metals such as chromium, arsenic, lead, mercury, etc. along with hazardous organic and inorganic wastes (e.g., acids, alkalies, cyanides, chlorides, etc.). Most of these pollutants are resistant to breakdown by microorganisms (called nonbiodegradable), therefore damage the growth of crops and the polluted water is unsafe for drinking purposes.
Factories manufacturing plastic, caustic soda and some fungicides and pesticides release mercury (a heavy metal) along with other effluents in nearby water body. Mercury enters the food chain through bacteria, algae, fish and finally into the human body. Fish died due to mercury consumption and those who ate fish were affected by mercury poisoning and quite a few died. The milder symptoms of mercury poisoning are depression and irritability but acute toxic effects can cause paralysis, blindness, insanity, birth defects and even death. The high concentration of mercury in water and in fish tissues results from formation of soluble monomethylmercury ion and volatile dimethylmercury by anaerobic bacteria in sediments.
C. Agricultural Waste: Manure, fertilizers, pesticides, wastes form farms, slaughterhouse, poultry farms, salts and silt are drained as run-off from agricultural lands. The water body receiving large quantities of fertilizers (phosphates and nitrates or manures becomes rich in nutrients which leads to eutrophication and consequent depletion of dissolved oxygen. Consumption of water rich in nitrates is bad for human health especially for small children.
Pesticides (DDT, dieldrin, aldrin, malathion, carbaryl etc.) are used to kill insect and rodent pests. Toxic pesticide residues enter the human body through drinking water or through food chain (biomagnification). These compounds have low solubility in water but are highly soluble in fats. For example, the concentration of DDT in river water may be very low but some fish over a period of time accumulate so much of DDT that they become unfit for human consumption. The use of pesticides in our country is increasing very rapidly. Some of these chemicals which are highly toxic become metabolised by animals that graze on fields. Therefore, these poisonous chemicals have been often observed in the humanfood chain. The presence of these chemicals in humans even in minute amounts can cause hormonal imbalance and may lead to cancer.
D. Physical Pollutants: Physical pollutants can be of different types. Some of them are discussed below-
(a) Radioactive Wastes : Radionucleides found in water are radium and potassium-40. These isotopes originate from natural sources due to leaching from minerals. Water bodies are also polluted by accidental leakage of waste material from uranium and thorium mines, nuclear power plants and industries, research laboratories and hospitals which use radioisotopes. Radioactive materials enter human body through water and food, and may be accumulated in blood and certain vital organs. They cause tumours and cancer.
(b) Thermal Sources: Various industries, nuclear power plants and thermal plants require water for cooling and the resultant hot water is often discharged into rivers or lakes. This results in thermal pollution and leads to the imbalance in the ecology of the water body. Higher temperature lowers the dissolved oxygen level (which is very essential for marine life) by decreasing the solubility of oxygen in water. Fish and other aquatic organism can get affected by a sudden change in water temperatures.
(c) Sediments : Soil particles carried to streams, lakes or oceans form the sediments. The sediment become polluting due to their large amount. Soil erosion defined as the soil carried by flood water from crop land, is responsible for sedimentation. The sediments may damage the water body by introducing a large amount of nutrient matter.
E. Petroleum Products: Petroleum products are widely used for fuel, lubrication, plastics manufacturing, etc. and happen to be poisonous in nature. Crude oil and other related products generally get into water by accidental spillage from ships, tankers, pipelines etc. Besides these accidental spills, oil refineries, oil exploration sites and automobile service centres pollute different water bodies. Oil slick which floats on the water surface causes death of marine life and severely affects the ecosystem of the ocean.

19. What are the effects of detergents on fresh water bodies?

Detergents destroy the external mucus layers that protect the fish from bacteria and parasites and also they can cause severe damage to the gills. Most fish will die when detergent concentrations approach 15 parts per million (ppm). Detergent concentrations as low as 5 ppm will kill fish eggs. Surfactant detergents are implicated in decreasing the breeding ability of aquatic organisms. Detergents also add another problem for aquatic life by lowering the surface tension of the water Phosphates in detergents can lead to freshwater algal blooms that releases toxins and deplete oxygen in waterways. When the algae decompose, they use up the oxygen available for aquatic life.

20. What are the various sources of groundwater pollution?

Sources of groundwater pollution are given below-
1. Storage Tanks: These tanks contain gasoline, chemicals, or petroleum oils that are present below the ground, the leakage of contaminants of these tanks into the groundwater can cause groundwater pollution.
2. Landfills: Landfills are the areas where the waste products and garbage are dumped. The landfills are supposed to have a protective layer for the prevention of contamination into the water. But if the layer is cracked or no such layer is present then it can cause contamination.
3. Septic tanks and systems: These are tanks and systems specially designed for the removal of household wastes. These are designed mainly for the removal of human waste products underground. The leakage of these tanks or pipes can lead to contamination of the groundwater system.

21. How is the disease 'methaemoglobinaemia' caused?

Methemoglobinemia (MetHb) is a very rare blood disorder, sometimes called blue baby syndrome, which affects how red blood cells deliver oxygen to cells and tissues. People can inherit this condition but MetHb usually happens when people use certain medications or recreational drugs or exposure to certain chemicals. MetHb can be life-threatening, especially for babies born with a severe type of the condition or people who use recreational drugs.

22. How can domestic waste be used as manure?

Depending upon the nature of the waste, domestic waste can be segregated into two categories i.e., biodegradable and non–biodegradable. Biodegradable waste such as leaves, rotten food, etc. should be deposited in land fills, where they get decomposed aerobically and anaerobically into manure. Non-biodegradable waste (which cannot be degraded) such as plastic, glass, metal scraps etc. should be sent for recycling.

23. What will be the problem arise due to abundance of phyto plankton?

Phytoplankton provides food for a wide range of sea creatures including shrimp, snails, and jellyfish. When too many nutrients are available, phytoplankton may grow out of control and form harmful algal blooms (HABs). These blooms can produce extremely toxic compounds that have harmful effects on fish, shellfish, mammals, birds, and even people.

24. Write in brief about sewage treatment.

Sewage is the liquid waste which includes house hold wastes, Industrial wastes ground wastes, etc. which contains 99.9 water with inorganic, organic matters in dissolved, suspension and colloidal states. It involves the following stages.
i. The removal of large solid particles. It can be done by screening and sedimentation. The solid wastes are deposited in land fillsites.
ii. It is allowed to stand is tanks. Many solids settle down by the use of the chemicals like alums and ferrousulphate while oil, grease, float on the surace which can be shimmed off.
iii. Next stage involve the biological oxidation of organic content of waste materials by microorganisms followed by filtration.
iv. Finally some physical and chemical processes are applied to remove some chemicals like phosphates and adding chlorine to improve the quality of waste water.

NIOS Sr. Secondary Chemistry Intext Questions of All Chapters with Answer