1. Dinitrogen and dioxygen are main constituents of air but these do not react with each other to form oxides of nitrogen because __________. (a) the reaction is endothermic and requires very high temperature. (b) the reaction can be initiated only in presence of a catalyst. (c) oxides of nitrogen are unstable. (d) N₂ and O₂ are unreactive. Ans: A
2. The pollutants which came directly in the air from sources are called primary pollutants. Primary pollutants are sometimes converted into secondary pollutants. Which of the following belongs to secondary air pollutants? (a) CO (b) Hydrocarbon (c) Peroxyacetyl nitrate (d) NO Ans: C
3. Which of the following is not a consequence of greenhouse effect? (a) Climatic conditions will be changed (b) Plants in warmer climates with adequate rainfall would grow faster (c) The incidence of infectious diseases is likely to increase (d) Malaria will be controlled as the mosquitoes will not survive. Ans: D
4. Which of the following gases is not a green house gas? (a) CO (b) O₃ (c) CH₄ (d) H₂O vapour Ans: A
5. The substance having the largest concentration in acid rain? (a) H₂CO₃ (b) HNO₃ (c) HCl (d) H₂SO₄ Ans: D
6. The non-viable particulate is among the following is (a) Dust (b) Bacteria (c) Moulds (d) Fungi Ans: A
7. Which of the following statements is not true about classical smog? (a) Its main components are produced by the action of sunlight on emissions of automobiles and factories. (b) Produced in cold and humid climate. (c) It contains compounds of reducing nature. (d) It contains smoke fog and sulphur dioxide Ans: A
8. Which of the following statements about photochemical smog is wrong? (a) It has high concentration of oxidising agents (b) It has low concentration of oxidising agent (c) It can be controlled by controlling the release of NO2, hydrocarbons ozone, etc. (d) Plantation of some plants like pinus helps in controlling photochemical smog. Ans: B
9. Which of the following statements is wrong? (a) Ozone is not responsible for green house effect. (b) Ozone can oxidise sulphur dioxide present in the atmosphere to sulphur trioxide. (c) Ozone hole is thinning of ozone layer present in stratosphere. (d) Ozone is produced in upper stratosphere by the action of UV rays on oxygen Ans: A
10. Which of the following statements is correct? (a) Ozone hole is a hole formed in stratosphere from which ozone oozes out. (b) Ozone hole is a hole formed in the troposphere from which ozone oozes out. (c) Ozone hole is thinning of ozone layer of stratosphere at some places. (d) Ozone hole means vanishing of ozone layer around the earth completely. Ans: C
11. Biochemical Oxygen Demand, (BOD) is a measure of organic material present in water. BOD value less than 5 ppm indicates a water sample to be __________. (a) rich in dissolved oxygen (b) poor in dissolved oxygen (c) highly polluted (d) not suitable for aquatic life Ans: A
12. Photochemical smog occurs in warm, dry and sunny climate. One of the following is not amongst the components of photochemical smog, identify it. (a) NO₂ (b) O₃ (c) SO₂ (d) Unsaturated hydrocarbon Ans: C
13. Phosphate pollution is caused by (a) sewage and agricultural fertilizers (b) weathering of phosphate rocks only (c) agriculutral fertilizers only (d) phosphate rocks and sewage Ans: A
14. The type of pollution caused by spraying of DDT (a) Air and soil (b) Air and water (c) Air (d) Air, water and soil Ans: D
15. Which among the following statements is false? (a) Oil slick in sea water increases D.O. value. (b) The main reason for river water pollution is industrial and domestic sewage discharge. (c) Surface water contains a lot of organic matter mineral nutrients and radioactive materials. (d) Oil spill in sea water causes heavy damage to fishery. Ans: A
16. Sewage containing organic waste should not be disposed in water bodies because it causes major water pollution. Fishes in such a polluted water die because of (a) large number of mosquitoes (b) increase in the amount of dissolved oxygen (c) decrease in the amount of dissolved oxygen in water (d) clogging of gills by mud Ans: C
17. Which of the following practices will not come under green chemistry? (a) If possible, making use of soap made of vegetable oils instead of using synthetic detergents. (b) Using H2O2 for bleaching purpose instead of using chlorine-based bleaching agents. (c) Using bicycle for travelling small distances instead of using petrol/ diesel based vehicles. (d) Using plastic cans for neatly storing substances Ans: D
18. Identify the wrong statement in the following: (a) Chlorofluorocarbons are responsible for ozone layer depletion. (b) Greenhouse effect is responsible for global warming. (c) Acid rain is mostly because of oxides of nitrogen and sulphur. (d) Ozone layer does not permit infrared radiation from the sun to reach the earth. Ans: D
19. Water is often treated with chlorine to (a) remove hardness (b) increase oxygen content (c) kill germs (d) remove suspended particles Ans: C
20. The greenhouse effect is because of the (a) presence of gases, which in general are strong infrared absorbers, in the atmosphere (b) presence of CO₂ only in the atmosphere (c) pressure of O₃ and CH₄ in the atmosphere (d) N2_O and chlorofluorohydrocarbons in the atmosphere Ans: A
21. Which of the following is/are the hazardous pollutant(s) present in automobile exhaust gases? (i) N2 (ii) CO (iii) CH4 (iv) Oxides of nitrogen (a) (ii) and (iii) (b) (i) and (ii) (c) (ii) and (iv) (d) (i) and (iii) Ans: C
22. Green chemistry means such reactions which (a) produce colour during reactions (b) reduce the use and production of hazardous chemicals (c) are related to the depletion of ozone layer (d) study the reactions in plants Ans: B
23. Which one of the following statement is not true? (a) pH of drinking water should be between 5.5 – 9.5. (b) Concentration of DO below 6 ppm is good for the growth of fish. (c) Clean water would have a BOD value of less than 5 ppm. (d) Oxides of sulphur, nitrogen and carbon are the most widespread air pollutant. Ans: B
24. Frequent occurrence of water blooms in a lake indicates (a) nutrient deficiency (b) oxygen deficiency (c) excessive nutrient availability (d) absence of herbivores in the lake Ans: B
25. When rain is accompanied by a thunderstorm, the collected rainwater will have a pH value (a) slightly lower than that of rainwater without thunderstorm (b) slightly higher than that when the thunderstorm is not there (c) uninfluenced by occurrence of thunderstorm (d) which depends upon the amount of dust in air Ans: A
26. The smog is essentially caused by the presence of (a) Oxides of sulphur and nitrogen (b) O₂ and N₂ (c) O₂ and O₃ (d) O₃ and N₂ Ans: A
27. Identify the wrong statement in the following. (a) Chlorofluorocarbons are responsible for ozone layer depletion. (b) Greenhouse effect is responsible for global warming. (c) Ozone layer does not permit infrared radiation from the sun to reach the earth. (d) Acid rain is mostly because of oxides of nitrogen and sulphur. Ans: C
28. Identify the incorrect statement from the following. (a) Ozone absorbs the intense ultraviolet radiation of the sun. (b) Depletion of ozone layer is because of its chemical reactions with chlorofluoro alkanes. (c) Ozone absorbs infrared radiation. (d) Oxides of nitrogen in the atmosphere can cause the depletion of ozone layer. Ans: C
29. What is DDT among the following ? (a) Greenhouse gas (b) A fertilizer (c) Biodegradable pollutant (d) Non-biodegradable pollutant Ans: D
30. The gas leaked from a storage tank of the Union Carbide plant in Bhopal gas tragedy was (a) Methyl isocyanate (b) Methylamine (c) Ammonia (d) Phosgene Ans: A
31. The substance which is not regarded as a pollutant? (a) NO2 (b) CO2 (c) O3 (d) Hydrocarbons Ans: B
32. The greatest affinity for haemoglobin is shown by which of the following : (a) NO (b) CO (c) O₂ (d) CO₂ Ans: A
33. Which of the following is not involved in the formation of photochemical smog? (a) Hydrocarbon (b) NO (c) SO₂ (d) O₃ Ans: C
34. The false statement among the followings : (a) The average residence time of NO is one month (b) Limestone acts as a sink for SOx (c) SOx can be removed from flue gases by passing through a solution of citrate ions (d) Ammonia acts as a sink for NOx Ans: A
35. The statement which is not correct about control of particulate pollution (a) In electrostatic precipitator, the particulates are made to acquire positive charge which are then attracted by the negative electrode and removed (b) Gravity settling chamber removes larger particles from the air (c) Cyclone collector removes fine particles in the diameter range 5-20 microns (d) Wet scrubbers are used to wash away all types of particulates Ans: A
36. Which of the following statements about polar stratosphere clouds (PSCs) is not correct? (a) PSCs do not react with chlorine nitrate and HCl (b) Type I clouds are formed at about –77ºC and contain solid HNO3 . 3H2O (c) Type II clouds are formed at about –85ºC and contain some ice (d) A tight whirlpool of wind called Polar Vortex is formed which surrounds Antarctica Ans: A
37. Minamata disease is due to pollution of (a) aresenic into the atmosphere (b) organic waste into drinking water (c) oil spill in water (d) industrial waste mercury into fishing water Ans: D
38. BOD is connected with (a) microbes and organic matter (b) organic matter (c) microbes (d) None of these Ans: A
39. Eutrophication causes reduction in (a) dissolved oxygen (b) nutrients (c) dissolved salts (d) All of these Ans: A
40. Which among the following statements is false? (a) Oil slick in sea water increases D.O. value (b) The main reason for river water pollution is industrial and domestic sewage discharge (c) Surface water contains a lot of organic matter mineral nutrients and radioactive materials (d) Oil spill in sea water causes heavy damage to fishery Ans: A
41. Presence of which of the following fuel gas in the exhaust fumes shows incomplete combustion of fuel? (a) Sulphur dioxide (b) Carbon monoxide and water vapour (c) Carbon monoxide (d) Nitrogen dioxide Ans: C
42. Which one of the following statements about ozone and ozone layer is true? (a) Ozone layer is beneficial to us because ozone cuts out the ultraviolet radiation of the sun (b) The conversion of ozone to oxygen is an endothermic reaction (c) Ozone has a triatomic linear molecule (d) None of these Ans: A

1. Consider the following:

1. Carbon dioxide 2. Oxides of Nitrogen 3. Oxides of Sulphur

Which of the above is/are the emission/ emissions from coal combustion at thermal power plants?

A. 1 only B. 2 and 3 only C. 1 and 3 only D. 1, 2 and 3

Answer - Option D
2. Human activities in the recent past have Caused the increased concentration of carbon dioxide in the atmosphere, but a lot of it does not remain in the lower atmosphere because of :

1. Its escape into the outer stratosphere. 2. The photosynthesis by phyto-plankton in the oceans. 3. The trapping of air in the polar ice caps.

Which of the statements given above is/are correct?

A. 1 and 2 B. 2 only C. 2 and 3 D. 3 only

Answer - Option C
3. Consider the following statements: Chlorofluorocarbons, known as ozone-depleting substances, are used

1. In the production of plastic foams 2. In the production of tubeless tyres 3. In cleaning certain electronic components 4. As pressurizing agents in aerosol cans

Which of the statements given above is/are correct?

A. 1, 2 and 3 only B. 4 only C. 1, 3 and 4 only D. 1, 2, 3 and 4

Answer - Option C
4. Acid rain is caused by the pollution of environment by

A. carbon dioxide and nitrogen B. carbon monoxide and carbon dioxide C. ozone and carbon dioxide D. nitrous oxide and sulphur dioxide

Answer - Option D
5. Photo-chemical smog is a resultant of the reaction among:

A. [latex]{NO}_{2}, {O}_{3}[/latex]and peroxyacetyl nitrate in the presence of sunlight B. CO, [latex]{O}_{2}[/latex] and 0 peroxyacetyl nitrate in the presence of sunlight C. CO, [latex]{CO}_{2}[/latex]and[latex]{NO}_{2}[/latex] at low temperature D. High concentration of [latex]{NO}_{2}, {O}_{3}[/latex], and CO in the evening

Answer - Option A
6. There is some concern regarding the nano-particles of some chemical elements that are used by the industry in the manufacture of various products. Why?

1. They can accumulate in the environment, and contaminate water and soil. 2. They can enter the food chains. 3. They can trigger the production of free radicals. Select the correct answer using the code given below.

A. 1 and 2 only B. 3 only C. 1 and 3 only D. 1, 2 and 3

Answer - Option D
7. Which of the following are some important pollutants released by steel industry in India?

1. Oxides of sulphur 2. Oxides of nitrogen 3. Carbon monoxide 4. Carbon dioxide

Select the correct answer using the code given below

A. 1, 3 and 4 only B. 2 and 3 only C. 1 and 4 only D. 1,2, 3 and 4

Answer - Option D
8. Brominated flame retardants are used in many household products like mattresses and upholstery. Why is there some concern about their use?

1. They are highly resistant to degradation in the environment. 2. They are able to accumulate in humans and animals.

Select the correct answer using the code given below.

A. 1 only B. 2 only C. Both 1 and 2 D. Neither 1 nor 2

Answer - Option C
9. The scientific view is that the increase in global temperature should not exceed 2 °C above pre - industrial level. If the global temperature increases beyond 3°C above the pre-industrial level, what can be its possible impact/impacts on the world?

1. Terrestrial biosphere tends toward a net carbon source 2. Widespread coral mortality will occur. 3. All the global wetlands will permanently disappear. 4. Cultivation of cereals will not be possible anywhere in the world.

Select the correct answer using the code given below.

A. 1 only B. 1 and 2 only C. 2, 3 and 4 only D. 1, 2, 3 and 4,

Answer - Option B
10. In the context of mitigating the impending global warming due to anthropogenic emissions of carbon dioxide, which of the following can be the potential sites for carbon sequestration?

1. Abandoned and uneconomic coal seams 2. Depleted oil and gas reservoirs 3. Subterranean deep saline formations

Select the correct answer using the code given below.

A. 1 and 2 only B. 3 only C. 1 and 3 only D. 1, 2 and 3

Answer - Option D
11. Biological Oxygen Demand (BOD) is a standard criterion for

A. Measuring oxygen levels in blood B. Computing oxygen levels in forest ecosystems C. Pollution assay in aquatic ecosystems D. Assessing oxygen levels in high altitude regions

Answer - Option C
12. In the context of solving pollution problems, what is/ are the advantage/advantages of bio-remediation technique?

1. It is a technique for cleaning up pollution by enhancing the same bio-degradation process that occurs in nature. 2. Any contaminant with heavy metals such as cadmium and lead can be readily and completely treated by bio-remediation using microorganisms. 3. Genetic engineering can be used to create microorganisms specifically designed for bio-remediation.

Select the correct answer using the code given below:

A. 1 only B. 2 and 3 only C. 1 and 3 only D. 1, 2 and 3

Answer - Option D
13. In potable water, the dissolved oxygen is stipulated as-

A. <6µg/l B. >6µg/l C. <6mg/l D. >6mg/l

Answer - Option A
14. In reference to Acid rain, what is correct statement

A. The pH value is below 5.6 B. It occurs due to presence of sulphuric acid or nitric acid in the atmosphere C. Maximum acid is due to strong Carbonic Acid D. Acid rain affects ecosystem

Answer - Option B
The exposure of gaseous pollutant sulphur dioxide may cause bronchitis and pulmonary emphysema
15. The working principle of turbidimeter is based on

A. reflection of light B. refraction of light C. scattering of light D. adsorption of light

Answer - Option C

1. The major source of carcinogenic hydrocarbon, benzo (α) pyrene present in urban atmosphere is

A. construction activities B. road traffic C. bursting of crackers D. domestic burning

Answer - Option B
Explanation -
Road traffic is the major source of carcinogenic hydrocarbon present in urban atmosphere.
2. The prescribed permissible noise level, Leq for commercial area at day time is

A. 75 dBA B. 50 dBA C. 55 dBA D. 65 dBA

Answer - Option D
Explanation -
The prescribed permissible noise level, Leq for commercial area at day time is 65 dBA. According to Central Pollution Control Board,

3. The global warming is caused by green house gases, which are

A. [latex]CO, {N}_{2}O, {CH}_{4} and CFC[/latex] B. [latex]{CO}_{2}, {NO}_{2}, {CH}_{4} and {H}_{2}O[/latex] C. [latex]{CO}_{2}, {N}_{2}O, {CH}_{4} and {H}_{2}O[/latex] D. [latex]{CO}_{2}, {NO}_{2}, {CH}_{4} and CFC [/latex]

Answer - Option C
Explanation -
Green house gases are the gas mixed in the atmosphere that absorbs the infrared radiation emitted by the earth’s surface.
We are not accustomed to these gases because neither nitrogen nor oxygen, the two most abundant gases of the atmosphere (78% and 21%, respectively), that many of us have heard of, have this ability to intercept infrared radiation.
4. Which of the following roles fly ash does not play in concrete

A. Improving the work ability B. Accelerating the strength gain C. Delaying the setting time of concrete D. Helps in long-term strength gain

Answer - Option B
Explanation -
Fly ash never improves strength of concrete. The advantages of using fly ash far outweigh the disadvantages. The most important benefit is reduced permeability to water and aggressive chemicals. Properly cured concrete made with fly ash creates a denser product because the size of the pores are reduced.
5. One turbidity unit NTU is equal to

A. 1.0 mg/l farmazin B. 1.0 meq/l [latex]{SiO}_{2}[/latex] C. 1.0 mg/l [latex]{SiO}_{2}[/latex] D. 1.0 meq/l kaolin

Answer - Option C
Explanation -
One turbidity unit NTU is equal to 1.0 mg/l Si[latex]{O}_{2}[/latex].
6. The prescribed permissible noise level, Leq for residential area at day time is

A. 65 dBA B. 45 dBA C. 50 dBA D. 55 dBA

Answer - Option D
Explanation -
The prescribed permissible noise level, Leq is 55 dBA.
According to Central Pollution Control Board,

7. Which of the following is not used as a supplementary cementations material?

A. Fly ash B. Gypsum C. Rice husk ash D. Silica fume

Answer - Option B
Explanation -
Gypsum is not used as a supplementary cementations material.
8. According to IS 456, if the maximum aggregate size is increased from 20 mm to 40 mm, the minimum cement content requirement changes (in kg/cum) by

A. – 20 B. 20 C.-30 D. 30

Answer - Option C
9. The turbidity in surface water is due to presence of

A. dissolved organics B. colloidal material C. dissolved in organics D. dissolved colors

Answer - Option B
Explanation -
Turbidity in surface water is due to colloidal material.
10. The prescribed permissible noise level , for residential area at night time is

A. 45 dBA B. 50 dBA C. 40 dBA D. 55 dBA

Answer - Option A
Explanation -
Explanation -
The prescribed permissible noise level, Leq is 45 dBA.
According to Central Pollution Control Board

11. The continuous exposure of high concentration of reparable suspended particulate matter may cause

A. eye irritation B. kidney damage C. failure of respiratory system D. cardiac disease

Answer - Option C
Explanation -
Explanation -
Continuous exposure to suspended particles are harmful to the lungs and can cause failure of respiratory system.
12. The prescribed permissible noise level, Leq for commercial area at night time is

A. 45 dBA B. 65 dBA C. 50 dBA D. 55 dBA

Answer - Option D
Explanation -
The prescribed permissible noise level, Leq for commercial area at night time is 55 dBA.
According to Central Pollution Control Board,

13. The pH of acid rain should always be less than

A. 5.6 even after precipitation B. 7.0 after precipitation C. 6.5 after precipitation D. 4.2 after precipitation

Answer - Option A
Explanation -
pH of acid rain should always be less than 5.6 even after precipitation.
14. The exposure of gaseous pollutant sulphur dioxide may cause

A. bronchitis and pulmonary emphysema B. lungs failure and kidney damage C. gastrointestinal problem D. the irritation in alveoli of the lungs

Answer - Option A
Explanation -
The exposure of gaseous pollutant sulphur dioxide may cause bronchitis and pulmonary emphysema
15. The machine ‘A' and machine ‘B' produce equal noise levels, i.e., 60 dBA each. The summation of these two noise levels is

A. 100 dBA B. 66 dBA C. 63 dBA D. 55 dBA

Answer - Option C

1. In stratosphere, the temperature increases with altitude due to presence of

A. radicals B. chlorofluorocarbons C. HCFCs D. Ozone

Answer - Option D
Explanation -
In the stratosphere, temperature increases with altitude. The reason is that the direct heat source for the stratosphere is the Sun. A layer of ozone molecules absorbs solar radiation, which heats the stratosphere. The amount of ozone present in the ozone layer is tiny, only a few molecules per million air molecules.
2. Nuclear density guage can be used for all the following purposes, except

A. Moisture content B. Wet density C. Dry density D. Standard penetration reading

Answer - Option D
Explanation -
Nuclear density gauge can be used for all the following purposes except standard penetration reading.
3. A water borne disease poliomyelitis is caused by

A. viruses B. protozoa C. bacteria D. helminthes

Answer - Option A
Explanation -
A virus that may cause paralysis and is easily preventable by the polio vaccine.
4. In potable water, the permissible limit of nitrate nitrogen is

A. 10 mg/l B. 25 mg/l C. 40 mg/l D. 15 mg/l

Answer - Option A
Explanation -
The permissible limit of nitrate nitrogen in potable water is 10 mg/l .
5. Carbon monoxide forms car-boxy hemoglobin in human blood that may cause

A. increased oxygen carrying capacity B. decreased oxygen carrying capacity C. damage in central nervous system D. damage in circulatory system

Answer - Option B
6. Two machines are working in a noisy environment and jointly product 55 dBA noise level. If the environmental noise level is also 55 dBA, the summation of noise levels is

A. 110 dBA B. 56 dBA C. 55 dBA D. 58 dBA

Answer - Option D
7. The average concentration of ozone present in the stratosphere is approximately

A. 5 ppm B. 0.05 ppm C. 10 ppm D. 15 ppm

Answer - Option C
Explanation -
The average concentration of ozone present in the stratosphere is approximately 10 ppm.
8. The total coliform bacteria are reported as most probable number (MPN) per

A. 10 ml of water B. 1000 ml of water C. 100 ml of water D. 1 ml of water

Answer - Option C
Explanation -
Total or fecal coli-form bacteria are reported as most probable number per 100 mL
9. The anthropogenic sources of air pollution in well planned city is

A. construction activities, road traffics, rail traffic, fugitive emissions B. construction activities, road traffic, domestic burning C. construction activities, road traffics, bursting of crackers, dust storms D. construction activities, road traffics, domestic burning, industrial emissions

Answer - Option B
Explanation -
Anthropogenic sources of air pollution in well planned city are construction activities, road traffics, and domestic burning.
10. When the measured and standard reference pressure level becomes equal, the sound pressure level (SPL) is equivalent to

A. 1 dBA B. 10 dBA C. 0 dBA D. 1.012 dBA

Answer - Option C
Explanation -
When the measured and standard reference pressure level becomes equal, the sound pressure level (SPL) is equivalent to 0 dBA.
11. The major green house gases contributing in global warming are

A. carbon dioxide, nitrous oxide, methane and water vapours B. carbon dioxide, sulphur dioxide, water vapours and chlorofluorocarbons C. carbon monoxide, nitrous oxide, methane and, hydro-chlorofluorocarbons D. carbon dioxide, nitrogen dioxide, water vapours , methane and ozone

Answer - Option A
Explanation -
The major green house gases contributing in global warming are carbon dioxide , nitrous oxide,methane and water vapor
12. The desirable amount of fluoride ions in potable waters for optimal dental health is:

A. 1.5 mg/l B. 1.0 mg/l C. 0.5 mg/l D. 0.05 mg/l

Answer - Option B
Explanation -
The desirable amount of flue le ions in potable waters for optimal dental health is 1.0 mg/l
13. Which of the following is not considered as secondary pollutant?

A. Photo chemical smog B. Peroxy acetyl nitrate C. Acid mist D. Carbon monoxide

Answer - Option D
Explanation -
Primary Pollutants Versus Secondary Pollutants

14. In the statistical distribution of noise levels, the back ground noise level is represented by:

A. [latex]{L}_{90}[/latex] B. [latex]{L}_{50}[/latex] C. [latex]{L}_{10}[/latex] D. [latex]{L}_{1}[/latex]

Answer - Option A
Explanation -
[latex]{L}_{90}[/latex] is frequently taken as the [latex]{L}_{p}[/latex] of the background level. [latex]{L}_{10}-{L}_{90}[/latex] is often used to give a quantitative measure as to the spread or “how choppy” the sound was. [latex]{L}_{10}[/latex] is the noise level exceeded for 10% of the time of the measurement duration.
15. Acid rain is caused due to formation of:

A. sulphuric acid and carbonic acid in the atmosphere B. sulphuric acid and nitric acid in the atmosphere C. nitric acid and carbonic acid in the atmosphere D. sulphuric acid, nitric acid and carbonic acid in the atmosphere

Answer - Option B
Explanation -
Scientists have discovered that air pollution from burning of fossil fuels is the major cause of acid rain. The main chemicals in air pollution that create acid rain are sulfur dioxide ([latex]{SO}_{2}[/latex]) and nitrogen ([latex]{NO}_{x}[/latex]). Acid rain usually forms high in the clouds where sulfur dioxide and nitrogen oxides react with water, oxygen, and oxidants. this mixture forms a mild solution of sulfuric acid and nitric acid. Sunlight increases the rate of most of these reactions. Rainwater, snow, fog, and other forms of precipitation containing those mild solutions of sulfuric and nitric acids fall to earth as acid rain.