The temperature of the troposphere generally decreases as altitude increases. The rate at which the temperature decreases is called the environmental lapse rate (ELR). 

Sulphur dioxide gas can cause acid rain in nearby places and air pollution in downwind areas from the volcanic site.

The troposphere is the lowest region of the atmosphere, i;e., closest to earth's surface. It extends roughly to a height of about 11 km. This is the region of all living organisms including, animals and plants. 

Acid rain is more properly called acidic deposition, which occurs in both wet and dry forms. Wet deposition usually exists in the form of rain, snow, or sleet but also may occur as fog, dew, or cloud water condensed on plants or the earth's surface. Dry deposition includes solid particles (aerosols) that fall to the earth's surface. Condensation of fog, dew, or cloud water is referred to as occult deposition.
The most common acidic substances are compounds containing hydrogen, sulphates, and nitrates. The chief source of these compounds is the combustion of fossil fuels such as coal, petroleum, and petroleum by-products, primarily gasoline.
Hence, acid rain is caused when air polluted by a large volume of sulphur dioxide.

Fifty percent of the total mass of the atmosphere is located in the lower $5-6$ $km$ of the troposphere. Nearly all atmospheric water vapour or moisture is found in the troposphere. So, it is the layer where most of the earth's weather takes place.

Solution:- (D) $1, \; 2$ and $3$

Acid rain is caused by a chemical reaction that begins when compounds like sulphur dioxide and nitrogen oxides are released into the air. These substances can rise very high into the atmosphere, where they mix and react with water, oxygen, and other chemicals to form more acidic pollutants, known as acid rain. Sulphur dioxide and nitrogen oxides dissolve very easily in water and can be carried very far by the wind. As a result, the two compounds can travel long distances where they become part of the rain, sleet, snow, and fog that we experience on certain days.
Hence, The pollutant in air responsible for acid rain is sulphur dioxide and nitrogen oxides.

Smog is well known for causing irritation in the eye. It may also result in inflammation in the tissues of lungs, giving rise to pain in the chest.

Smog is a thick fog-like layer in the atmosphere, especially during winters, made up of fog and smoke. 

Smog can be defined as a mixture of various gases with dust and water vapour.

Buildings are eroded by acid rains. When acid rain makes way into lakes, rivers it affects the aquatic life and affects the forests by affecting the minerals uptake of the plants.

When oxides of sulphur and nitrogen emitted by the industries, react with the moisture present in the atmosphere they form acids.

Heavy smog is responsible for decreasing the UV radiation greatly.

Smoke is a form of dry deposition of acid rain.

Acid rains are caused when the pollutants such as sulphur dioxide and nitrous oxide formed due to the burning of the fossil fuels are released in the atmosphere, where they travel upwards and mixes with oxygen, air and moisture to form pollutants called acidic oxide pollutants.

The pH of acid rain is in the range 3.5 to 5.6 . Typical value can be 4.0 .

The causes of acid rain are:

Wet deposition is rain, sleet, snow, or fog that has become more acidic than normal. Wet deposition of acids occurs when any form of precipitation removes acids from the atmosphere and delivers it to the Earth's surface.

Acid rain includes any form of precipitation with acidic components from the atmosphere.

${ SO } _{ 2 }$ and ${ NO } _{ 2 }$:burning of fossil fuels releases oxides of sulphur and nitrogen, ${ SO } _{ 2 }$ and ${ NO } _{ 2 }$ reacts with water and oxygen and other chemicals to form sulphuric acid and nitric acid.

 Acid rain is caused by emissions of acidic gases like sulphur dioxide, nitrogen and carbon oxides, which react with the water  molecules in the atmosphere to produce acids. 

SO2SO2 is formed as a major pollutant. So, lung diseases are four times more in urban areas than in rural areas.

Below are few properties of acid rain:
1) Acid rains are obtained due to oxides of nitrogen & sulphur.
2) Nitric acid and sulphuric acid in the atmosphere dissolve in rain water and come down to earth as acid rain. 
3) It may have a pH less than 5.6
4) There is no relation of acid rain with ozone layer.

The water-gas shift reaction (WGSR) describes  the reaction of carbon monoxide and water vapour to form carbon dioxide and hydrogen (the mixture of carbon monoxide and hydrogen is known as water gas)

Acid rain caused by emissions of sulphur dioxide and nitrogen oxide, which react with water molecules in the  atmosphere to produce corresponding acids.

Smog is a dark brown or greyish smoky mist that occurs in cold weather. It is formed by unburnt carbon particles or hydrocarbons suspended in the air. It is a visible indication of air pollution. Smog not only reduces visibility but is highly suffocating and harmful to human beings, animals and plants.

Acid rain is caused by oxides of sulphur and nitrogen. 
The sulphur dioxide gas released during burning of coal and oxides of nitrogen released during combustion of petrol dissolve in rain water and form acids such as sulphuric acid and nitric acid. these acids drop down with rain which makes rain acidic.

Because insects have the ability to digest silk and wool. Examples of insects that damage the clothes are-silverfish, cockroach, moth etc. 

Acid rain is a rain or any other form of precipitation that is unusually acidic, meaning that it possesses elevated levels of hydrogen ions or low pH. it can have harmful effects on plants, aquatic animals, and infrastructure. It is a result of air pollution. When oxides of sulfur or nitrogen react with water sulfuric acid or nitric acid is formed.

Smog is a type of air pollutant, is a combination of smoke and fog. Classic smog results from large amounts of coal burning in an area and its caused by a mixture of smoke and sulphur dioxide.

Smog is often caused by heavy traffic, high temperatures, sunshine and calm winds.

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 ($SO _2$) and nitrogen oxides. 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.

The main chemicals in air pollution that create acid rain are $SO _2$ and $NO _x$. 

The damages caused by acid rain are:

$\displaystyle NO+{ O } _{ 2 }\rightarrow { NO } _{ 2 }$ is the incorrect equation as it is not balanced. 

Industries like Mathura Oil refinery near Agra emits certain suspended particulate matter like soot particles. This results in yellowing of marble of the monument.

When oxides of sulphur and nitrogen which are emitted by the industries, react with the moisture present in the atmosphere, they form acids.

Acid rain is caused due to oxides of nitrogen and sulphur reacting with water, oxygen, carbon dioxide, and other chemicals present high in the atmosphere resulting into acidic pollutants.

At ground level, ozone is an air pollutant that is a major component of smog which is dangerous for both humans and plants. Long-term ozone exposure has also been shown to reduce life expectancy. 

Acid rain is a rain or any other form of precipitation that is unusually acidic, meaning that it possesses elevated levels of hydrogen ions (low pH). It can have harmful effects on plants, aquatic animals and infrastructure. Acid rain is caused by emissions of sulfur dioxide and nitrogen oxide, which react with the water molecules in the atmosphere to produce acids. 

Over a number of years the average pH of a stream changes from a pH of 6.9 to a pH of 5.9 due to acid rain. The pH of the stream is now 10 times more acidic than it was years ago.
Years ago, the pH was 6.9. The present day pH is 5.9. The change in pH is
$\displaystyle  = \Delta pH= 5.9-6.9 = -1$
The corresponding change in hydrogen ion concentration is:
$\displaystyle 10^{-\Delta pH}= 10^{-(-1)} = 10$

The major natural causal agent for acid rain is volcanic emissions. Volcanoes emit acid producing gases to create higher than normal amounts of acid rain or any other form of precipitation such as fog and snow to an extent of affecting vegetation cover and health of residents within the surrounding. 

Carbon dioxide would react with rainwater to produce acid rain.

The principal cause of acid rain is sulfur and nitrogen compounds from human sources, such as electricity generation, factories, and motor vehicles. Electrical power generation using coal is among the greatest contributors to gaseous pollutions that are responsible for acidic rain. The gases can be carried hundreds of kilometers in the atmosphere before they are converted to acids and deposited.

Photochemical smog is the chemical reaction of sunlight, nitrogen oxides and volatile organic compounds in the atmosphere, which leaves airborne particles and ground-level ozone.
Hence option A is the correct answer.

Smog is two types:-
1) Classical smog is also called as London smog or sulphurous acid smog.
2) Photochemical smog is also called as Los angles smog.

The troposphere is the lowest portion of earth's atmosphere and is also where all weather takes place. It contains approximately 75% of the atmosphere's mass and 99% of its water vapour and aerosols.

Smog is two types:
1) Classical smog is also called as London smog or sulphurous acid smog.
2) Photo chemical smog is also called as Los angles smog.

$ {S}{O} _{2} $ produces acid rain. It reacts with atmospheric oxygen to produce $ {S}{O} _{3} $. This sulphur trioxide reacts with water to produce Sulphuric Acid. Thus acid rain is produced.

Smog is two types:
1) Classical smog is also called as London smog or sulphurous acid smog.
2) Photochemical smog is also called as Los angles smog. 
Hence option D is correct.

The main constituents of acid rain are sulphuric acid and nitric acid. Hydrochloric acid is also present in acid rain in small amount.

Stratosphere ranges from 20-50 km. It is the layer above troposphere. Stratosphere contains ozone as it's main species.

$SO _2$ is a major gaseous pollutant found in the lower atmosphere. They are the compounds of sulphur and oxygen molecules. So when the fuels such as coal and oil are burnt, it leads to emission of $SO _2$ gas. 

$SO _2, O _3, NO _x$ causes pollution. They are examples of smog or photochemical smog. But $H _2$ being a clean fuel does not pollute the air.

Acid rain is the state when the pH of rain falls below 5.6.  Acid rain damages the buildings and statues as they dissolve and corrodes the heavy metals. This happens when sulphuric acid nitric acids in the polluted air react with calcite in marble, the calcite dissolves. It also dissolves metals from soils, rocks and sediments.  

Acid rain is the state when pH of rain falls 5.6. It is mainly due to the presence of oxides of sulphur and nitrogen ( $ NO _2 $ and  $ SO _2 $ in the atmosphere. They are transported into the atmosphere by wind an other air currents. 

Residence time means the lifetime amount of chemicals in the atmosphere divided by the rate at which the chemicals are eliminated from the atmosphere. The average residence time of NO is 0.5 to 2 days. 

The main component of acid rain are sulphuric acid, nitric acid and carbonic acid that are present in atmosphere due to cars and industries and factory waste. Human actions like using detergent, releasing pesticides and fertilizers in water lead to acid rain.

Water-soluble pollutants are detergents, fertilizers, oils from factories and industries, ammonical nitrogen etc. Whereas oxides of nitrogen, carbon, and sodium are air pollutants that cause gaseous pollution. 

Peroxyacetyl nitrate is a secondary pollutant since they form in the atmosphere after the emission of primary pollutants. It is present in photochemical smog.

Surface water getting contaminated with PCB waste generally has high levels of PCBs in sediment, as the PCBs attach to organic matter. PCBs can be slowly released from the sediment into the water and evaporate into the air.

Sulfur dioxide another toxic chemical gas when combines with water and air, forms sulfuric acid, which is the main component of acid rain. Carbon dioxide in the air can dissolve in rainwater to form carbonic acid, $H _{2}CO _{3}$ and contributes to acid rain.

IR active molecules in the atmosphere can increase their vibrational energy by absorbing some of this infrared light, and thus increasing the temperature of the atmosphere resulting in Global warming.

The correct option is A.

The main source of pollution in metro cities is automobile exhausts. 

The pH of the acid rain is approximately 5-6.

When gases like $NO _2$ and $SO _3$ go into the atmosphere and react with water and form $H _2SO _4$ and $HNO _3$, these acids come along with rain water and hence it is known as acid rain.