Shell of many marine organism are made of calcium carbonate. Carbonate is formed when carbon dioxide (CO2) from atmosphere get react with the sea water. It also help us to maintain carbon dioxide level in the atmosphere because today scenario is very alarming due to increasing level of carbon dioxide. 

Major causes of air pollution are combustion of natural gas, coal, petroleum, automobiles, aircraft, railways, thermal plants, welding, stone crushing and agriculture burning

Water pollution is the mixing of contaminants to the water bodies (e.g., lakes, rivers, oceans, aquifers and groundwater) which changes the desired quality of water. Water pollution affects the entire biosphere, plants and organisms living in these bodies of water.

Water pollution affects the entire biosphere, plants and organisms as all the life forms depend on water for their survival. In almost all cases, the effect is damaging not only to individual species and population but also to the natural biological communities. 

Pollution is the addition of contaminants into the natural environment that can cause undesirable change. It may be the chemical and physical change. Pollutants are the contaminants that cause pollution.

Fine organic or inorganic particles suspended in air is called as aerosol particulate matter. It consists of soot, flash, and dust of various types, fur, hair, spores etc. It is classified into settleable and suspended particulate matter.

Carbon dioxide is described as pollutant or not a pollutant depending on the source of emission. The carbon dioxide which is released from the plants and animals as the end product of the respiration is not considered as a pollutant. The carbon dioxide gas which is released as the exhausts and emissions from the industries causes pollution and are referred as a pollutant. The main role of the gas is in increasing the temperature of Earth and so these are not pollutants. 

The full form of PAN is Peroxyacetyl nitrate. It is a major pollutant of smog which has adverse effects on eyes and lungs. Therefore the correct answer is B.

CO reacts with haemoglobin much faster than oxygen. It can be fatal to life. If the amount of CO is high, it forms carboxy haemoglobin on combination with haemoglobin which causes suffocation even leads to death in fetal condition. Thus, the correct answer is option D.

According to the WHO, the most polluted city in the world in 2016 is Zabol in Iran with particulate matter concentration of 2.5. This is more than 20 times higher than the WHO's guidelines. Thus the correct answer is option A.

Particulate pollutants are the mixture of small solid particles and liquid droplets. It consists solid particles like soot, flash, dust of various types, fir, hair, spore etc. It is classified as the suspended particulate matter which is the source of pollution and may adversely affect the environment. It can cause harmful effects on health on inhaling it.

Hydrocarbons are nonbiodegradable pollutants. They are a type of secondary pollutants. They are very dangerous for life. Hydrocarbons are produced naturally as well as due to incomplete combustion of the fuels. They are the major cause of respiratory disorders. Man used fuel for their own purpose with releases harmful gasses and causes pollution.

The atmosphere comprises of layers based on temperature. Each layer has a specific composition of gases. These layers are the troposphere, the stratosphere, mesosphere and thermosphere. All these layers are placed to a different level from the earth. 

The presence of CFCs in the atmosphere results in the depletion of the ozone layer. They are used as coolants in refrigerators, aerosol sprays, coolers, etc. The increase in the concentration of the chloro- fluoro-hydrocarbon molecules in the atmosphere results in air pollution. 

• Classical smog is formed when there is high concentration of sulphur dioxide and particulate matter produced due to combustion of fuels. It occurs in cold and humid climate. It is also known as London smog or Sulphurous smog and causes dark brownish colour of atmosphere.
• Photochemical smog is formed when sunlight acts on the oxides of nitrogen and hydrocarbons produced from factories or by automobiles. It occurs in warm and dry climate. It is also known as Los Angeles smog and causes light brownish colouration of atmosphere.

In human, effect of Hydrogen sulfide due to air pollution is not seen but in plant it greatly effect like chlorosis ( yellowish color of plant leaves). Falling of leaves is also a major problem (defoliation). Hydrogen sulfide also damage building, bridge paints (discoloration).

The presence of pollutant adversely affect the plants. Reduction in chlorophyll is caused by toxic ions formed by the dissolution of SO$ _2$ in water inside leaf tissue, which preferentially incorporate into thylakoid membrane disturbs the photosystems. The oxides of sulphur transform into several poisonous substances which hamper the growth of the plants.

The increase in the concentration of the air pollutants results in an adverse effect on the plants and animal health. SO$ _2$ is considered as one of the pollutants which causes bleaching of the plants. The chlorophyll pigments in the leaves of the plants are destroyed in the presence of increased amounts of sulfuric acid which is formed by reacting with the water in plants. 

Ozone is a toxic gas which causes severe effects on the body on inhalation. The gas causes irritation in the nose, throat and other parts of the respiratory system. Inhalation of about 0.1 ppm of the gas may result in effects like swelling and bleeding of the lungs. Haemorrhage of the lungs, stomach and intestine is a common effect of the ozone breathing. 

Fuels burn when they react with oxygen in the air. If there is plenty of air, complete combustion happens.  Coal is mostly carbon. During complete combustion, carbon is oxidized to carbon dioxide:
carbon + oxygen -- carbon dioxide
If there is insufficient air for complete combustion, incomplete combustion (also called partial combustion)  happens. Hydrogen is still oxidized to water, but carbon monoxide forms instead of carbon dioxide.

A heat island is an area that is constantly warmer than surrounding areas. One of the reasons for the formation of heat island is air pollution. Other important reasons are changes in landscape due to the construction of buildings, roads, and other infrastructure which had replaced open land and vegetation. An island formation is the result of local changes in the environment brought about by urbanisation and release of polluting gases.

A major threat to Taj Mahal is from Mathura oil refinery due to polluting gases like sulphur dioxide, hydrogen sulphide and nitrogen oxides.  When moisture gets accumulated in polluted environment, the oxides of sulfur, carbon and nitrogen from weak sulfuric, carbonic and nitric acids which are corrosive of stone, metals, paints and textiles.  Many priceless works of art have suffered more damage in the last 20 years due to increased sulfur-dioxide in the atmosphere.

Leaves are directly exposed to air pollutants and effects of air pollution are first seen on leaves. Deposition of particulate matter hampers gaseous exchange and deposition of soot interfere with the capture of sunlight. Sulphur dioxide causes the destruction of chlorophyll and necrosis. Nitrogen oxides cause defoliation, necrosis, dieback and death of plants. Other than this, acid rain damages plant by a direct effect on foliage and growing points by chlorosis, necrosis, defoliation and dieback.

A thermal inversion takes place when a layer of warm air settles over a layer of cooler air that lies just above the ground. The warm air holds down the cool air and prevents pollutants from rising and scattering.

Inhalation of SO$ _2$ irritates the nose, throat, and airways to cause coughing, wheezing, shortness of breath, or a tight feeling around the chest. The effects of sulphur dioxide are felt just after 10-15 min of inhalation.

The Mathura Refinery situated close to the Taj Mahal is a threat to the marble of the Taj Mahal because the Refinery releases the air pollutants in the form of oxides of sulphur, oxides of nitrogen and oxides of carbon. These oxides then react with water and precipiate in the form of nitric acid and sulphuric acid called acid rains. Acid rains have resulted in the corrosion of the marble, making it to appear yellow. Hence, the correct answer is 'Air Pollutants from Mathura Refinery'.

Air pollution is responsible for various pulmonary or respiratory diseases like asthma, emphysema, bronchitis etc. 

In a thermal inversion, the cold air holds up the pollutants and prevents it from rising and scattering.

The heat island is a phenomenon where heat can no longer escape. The high temperature in urban areas as compared to rural areas can be called heat island effect. With the loss of vegetation and land surface in urban areas, heat gets trapped between buildings and dense areas which cause a warming effect. The air pollution due to greenhouse gases is responsible for this. Bigger cities have large heat island effects, the waste heat from energy use, seasonal changes, local weather also contribute to heat islands.

• Classical smog, also known as London smog or Sulphurous smog, is formed when there is high concentration of sulphur dioxide and particulate matter produced due to combustion of fuels. It occurs in cold and humid climate and has reducing nature.
• Photochemical smog, also known as Los Angeles smog, is formed when sunlight acts on the oxides of nitrogen and hydrocarbons produced from factories or by automobiles. It occurs in warm and dry climate and has oxidising nature.

• Classical smog, also known as London smog or Sulphurous smog, is formed when there is high concentration of sulphur dioxide and particulate matter produced due to combustion of fuels. It occurs in cold and humid climate and has reducing nature.
• Photochemical smog, also known as Los Angeles smog, is formed when sunlight acts on the oxides of nitrogen and hydrocarbons produced from factories or by automobiles. It occurs in warm and dry climate and has oxidising nature.

• Motor vehicle emissions are one of the causes of poor air quality. Other causes include wood-burning fires, fires on agricultural land, exhaust from diesel generators, dust from construction sites, burning garbage and illegal industrial activities in Delhi.
• Air pollution exposure can trigger new cases of asthma, exacerbate (worsen) a previously-existing respiratory illness, and provoke development or progression of chronic illnesses including lung cancer, chronic obstructive pulmonary disease, and emphysema. If untreated result in death.
  
• An annual number of deaths in Delhi believed to be due to air pollution is 7500.
  
• So, the correct answer is '7500'.

There are a number of chemicals, which causes lung cancer and one of them is 3, 4- benzopyrene. Benzopyrene mutates three key positions in the p53 gene, which leads to lung cancer. Hence, the correct answer is option C.

Acid rain is a mixture of wet and dry deposition (deposited material) from the atmosphere containing higher than normal amounts of nitric and sulfuric acids. Sulfur dioxide ($SO _2$) and nitrogen oxides (NOx) are the principal pollutants, that cause acid precipitation. $SO _2$ and NOx emissions released to the air react with water vapor and other chemicals to form acids that fall back to earth. The majority of NOx comes from cars, buses, trucks, and other forms of transportation and from power plants. Therefore, the correct answer is option E.

Skeletal fluorosis or osteoporosis is a bone disease caused by excessive accumulation of fluoride in the bones. In advanced cases, skeletal fluorosis causes pain and damage to bones and joints. Due to a high fluorine concentration in the body, the bone is hardened and thus less elastic, resulting in an increased frequency of fractures. Other symptoms include thickening of the bone structure and accumulation of bone tissue, which both contribute to impaired joint mobility. Ligaments and cartilage can become ossified. As a result, bone flexibility decreases making the bone more amenable to fractures.

Airborne fluorides have caused more worldwide damage to domestic animals than any other air pollutant. Fluoride is not biodegradable and gradually accumulates in the environment through the food chain, in human and animal bodies, where it settles in bones and teeth. Thus, the correct answer is option A.

Pollution is defined as addition of harmful components in the environment which alters the composition of an environment. The harmful component is known as pollutant. Enriched air, also called as oxygen enriched air, or nitrox has more oxygen in it. The two most commonly used nitrox mixtures are 32% and 36% oxygen with less nitrogen. The most common use of nitrox mixtures containing higher than normal levels of oxygen is in scuba diving. The result of breathing elevated partial pressures of oxygen is hyperoxia, an excess of oxygen in body tissues. 

Air pollution can directly affect plants via leaves or indirectly via soil acidification. When exposed to pollutants, most plants experience physiological changes before exhibiting visible damage to leaves like necrosis, chlorosis. The atmospheric SO$ _2$ adversely affects various morphological and physiological characteristics of plants through acid rain. 

Pollution in all forms can cause a disturbance in the ecosystem. Melting of glaciers can cause rising in sea levels, which increase the threat of mixing fresh and salt water and the species can be extinct, the food chain can be disrupted, climatic change can cause instability, several areas might become prone to erosions, landslides, heavy rainstorms can cause migrations and crisis of survival. When the abiotic environment is disturbed, the worst effects are finally faced by the biotic environment.

Bio gas is a natural gas produce through anaerobic decomposition of organic wastes. This burn with blue flame without producing fumes. It can be easily compressed and transported.

The visibility of less than 1 km is the standard range for fog, that is formed due to condensation of the water droplets near earth's surface. Mist is formed due to the dispersion of dust and smoke in the air along with nucleation of the water droplets and the visibility range for mist is between 1 km to 2 km. The visibility range for haze is between 2 km to 5 km.

In Tokyo, the excessive accumulation of the air pollutants in the atmosphere have severely deteriorated the oxygen availability because the primary pollutants like nitrogen oxides, sulphur oxides, hydrocarbon react with oxygen to form the ozone, PAN etc. So, the people working in fields like traffic policemen suffer from severe deoxygenation. So, they need hyperbaric oxygen treatment daily.

Waldsterben refers to the mass death of the trees wherein, the peripheral parts of the plants are killed and slowly the entire forest population dwindles. It was first reported in Germany in the early 1980s. The atmospheric pollution was the main cause of such deaths of trees. Tropospheric ozone is the secondary pollutant. Nitrogen oxides and sulphur oxides are released by the industrial emissions and vehicular exhausts. Acid rain is the chemical reaction between these oxides and water to form their respective acids that precipitate with the rains. The pollutants have severe effects on the trees.

The big cities in India have witnessed an ever increase in the air pollution and deterioration of the air quality due to the increase in the use of the vehicles, construction material, industrial growth, deforestation etc. The increase in the suspended particles, the frequent appearance of the photochemical smog, the events of the acid rains and the increase in respiratory diseases in the population are the outcomes of air pollution. 

Atmospheric aerosol particles can be defined as any solid or liquid droplets suspended in the atmosphere. Fog, Dust, smoke are examples of aerosol. Aerosols increase atmospheric albedo due to which the rate of photosynthesis by plants on earth is decreased. Albedo is the part of the energy from the sunlight reflected back into the atmosphere. 

Biotic components are living things and abiotic components are non-living being in an ecosystem. Pollution of any kind adversely affect these components, contaminated air affects the natural cycle of respiration for trees, human and animals, excessive use of fertilisers diminish the quality of soil and malign the quality of water. Smoke and chemical production cause ozone depletion. Lands are becoming infertile, natural water bodies are drying up, and with the development new kind of pollution can be identified such as nuclear pollution making soil, water and atmosphere radioactive for long period.

Lead is the major heavy metal pollutant released by the vehicular exhausts. It persists in the air and precipitates with the rains. In reaches the human body when consumed through water or inhaled as suspended particle. At the concentration of 30μg/100ml in blood, it is considered poisoning as it can cause aplastic anaemia, tumour and cancer.

Lead is the major heavy metal pollutant released by the vehicular exhausts. It persists in the air and precipitates with the rains. In reaches the human body when consumed through water or inhaled as suspended particle. At the concentration of 30μg/100ml in blood, it is considered poisoning as it can cause aplastic anaemia, tumour and cancer.

In foggy and hazy environment, the visible spectrum of the sun is not able to penetrate and so, humans find it difficult to visualize. However, the UV-A can penetrate through the fog, which cannot be detected by human eyes as t falls behind the visible spectrum of VIBGYOR. Birds are capable of recognizing more colors than the humans, they can detect the UV rays as well that allows them to navigate in the foggy and hazy conditions as well. These also allow the birds to track their migratory routes.

Photochemical smog is composed mainly of ozone (O$ _3$), Peroxyacetyl nitrate (PAN) and NOx. It is often called brown air where solar radiation is intense. In areas or seasons of lesser solar radiation smog formation is incomplete and the air is referred to as grey air.

Anthracosis is the clinical disorders of the respiratory tract that is caused due to deposition of the coal dust due to inhalation of polluted air. It is a form of pneumoconiosis. Due to this, the lungs are rendered black in colour. It is also called the Miner's disease as the coal mine workers are worst affected by it. It affects the bronchi and alveoli surface area. This illness can be seen in smokers as well. Pulmonary emphysema and chronic bronchitis are the severe effects of anthracosis. 

Aerosols are minute particles suspended in the atmosphere and are known to reduce primary productivity on earth. scattering and absorption of sunlight by anthropogenic aerosols reduce photosynthetically active radiation, (PAR) incident upon the Earth’s surface, but increase the fraction of the PAR that is diffuse.

Hydrogen cyanide stops the transport of oxygen around the body and may also cause sudden loss of consciousness, weakness, headache, confusion, nausea, vomiting, irritation and eye infections. People with sensitive kidneys, respiratory tract (air passages and lungs), skin or thyroid are more prone to hydrogen cyanide poisoning. Part of the reason why hydrogen cyanide is considered potentially more dangerous is that some individuals are unable to detect it by smell which creates damage to neurons.

When there is temperature difference between the land and the atmosphere, and the land is also having low temperature, then the condensation of the water droplets/water vapours can begin near the surface. The condensation process occurs around the dust particles present in the air, so the dust particles provide nucleation for fog formation. Smoke and dust forms the haze. Smoke, dust and water droplets form the mist. Hence, the correct answer is ‘Condensation of water vapours over dust particles’.

Substances that are not broken down by microorganisms are non-biodegradable. Non-biodegradable substances affect the soil. Biodegradable substances are broken down by organisms and are not harmful to environment. Hence, non-biodegradable and industrial wastes are considered as soil pollutants. They may enter the food chain and harm the organisms in the higher trophic levels. 

Wastes are mainly of two types, biodegradable and non-biodegradable. Biodegradable wastes are not harmful to soil as they are broken down by microorganisms. Non-biodegradable wastes like hazardous waste, radioactive waste, electronic waste, etc., are harmful to the soil. These are soil pollutants which may enter the food chain and harm the organisms in the higher trophic levels. 

Soil pollution is caused by removal or addition of substances and factors which decrease its productivity. It is caused by agrochemicals, industrial wastes, municipal wastes etc. It adversely affects the fertility of the soil.

Soil contamination or soil pollution is caused by the presence of human-made chemicals or other alteration in the natural soil environment. It is typically caused by industrial activity, agricultural chemicals or improper disposal of waste. The most common chemicals involved are petroleum hydrocarbons, polynuclear aromatic hydrocarbons, solvents, pesticides, lead and other heavy metals. 

Soil pollution is caused by the addition of substances which decrease its productivity. It is caused by agrochemicals, industrial wastes, municipal wastes etc. It adversely affects the fertility of the soil. Pesticides are used in agricultural practices and these chemicals penetrate into the soil and changes the pH of the soil. Also, pesticides affect the fertility of soil by decreasing the number of soil microorganisms. 

Photosynthesis, process by which green plants and certain other organisms use the energy of light to convert carbon dioxide and water into the simple sugar glucose. In so doing, photosynthesis provides the basic energy source for virtually all organisms. So, the correct option is "D" (Photosynthesis).

CFC is found to destruct the ozone layer. It is found to be contaminating air. Cooling electronic gadgets are the major source of CFC.