Environmental Study Questions in English

(B) $Acid \ rain$ contains $H_2SO_4$ and $HNO_3$,which react with the calcium carbonate $(CaCO_3)$ present in the marble of the $Taj \ Mahal$.
This chemical reaction leads to the corrosion and discoloration of the monument.

(C) The presence of $SO_2$ in the atmosphere is a known pollutant that affects plant physiology. High concentrations of $SO_2$ cause the stiffness of flower buds,leading to their eventual shedding.

(A) Photochemical smog is formed by the reaction of nitrogen oxides $(NO_x)$,volatile organic compounds $(VOCs)$,and ozone $(O_3)$ in the presence of sunlight.
$N_2$ is an inert gas that constitutes about $78\%$ of the atmosphere and does not participate in the chemical reactions that lead to the formation of photochemical smog.

(C) The $BOD$ (Biochemical Oxygen Demand) value is a measure of the amount of dissolved oxygen required by bacteria to decompose organic matter in water.
Clean water typically has a $BOD$ value of less than $5 \ ppm$.
Highly polluted water typically has a $BOD$ value of $17 \ ppm$ or more.
Therefore,a water sample with $4 \ ppm$ is considered clean,and a water sample with $18 \ ppm$ is considered highly polluted.

(D) Photochemical smog is formed by the action of sunlight on unsaturated hydrocarbons and nitrogen oxides.
Its common components include ozone $(O_3)$,nitric oxide $(NO)$,acrolein $(CH_2=CHCHO)$,formaldehyde $(HCHO)$,and peroxyacetyl nitrate ($PAN$,$CH_3-C(=O)OONO_2$).
$CF_2Cl_2$ (Freon-$12$) is a chlorofluorocarbon $(CFC)$ which is responsible for ozone layer depletion in the stratosphere,but it is not a component of photochemical smog.

(A) The ozone layer in the upper stratosphere absorbs harmful ultraviolet $(UV)$ radiation from the sun.
This radiation typically falls in the wavelength range of $200-315\, nm$ (often cited as $200-340\, nm$ depending on the specific $UV$ band classification).
Among the given options,$200-315\, nm$ is the correct range for the radiation filtered by the ozone layer.

(B) Using plastic bags is harmful to the environment because plastics are non-biodegradable and cause pollution. Therefore,it is against our responsibility to protect the environment.

(C) The upper stratosphere contains the ozone layer $(O_3)$,which protects the Earth from harmful ultraviolet $(UV)$ radiation from the Sun. $CFCs$ (chlorofluorocarbons) released into the atmosphere reach the stratosphere,where they undergo photochemical decomposition to release chlorine radicals. These radicals catalyze the destruction of ozone,leading to the formation of ozone holes. Consequently,these ozone holes allow a higher intensity of $UV$ radiation to reach the Earth's surface. Therefore,both statements are correct,and the reason explains the consequence of the phenomenon described in the assertion.

(B) The maximum prescribed concentration of copper in drinking water is $3 \ ppm$.
Above this concentration,water becomes toxic.

(C) Carbon dioxide is very important for maintaining the climate which is suitable for our survival.
$CO_2$ has the property of trapping heat from the sun. So,higher the level of carbon dioxide,the higher will be the heat trapped.
This leads to the rise in the temperature of the earth,resulting in global warming.
Therefore,we can say excessive release of $CO_2$ into the atmosphere results in global warming.

(C) The atmosphere is divided into layers based on temperature variations with altitude.
The layer extending from approximately $10 \, km$ to $50 \, km$ above sea level is known as the stratosphere.

(B) The $Troposphere$ is the lowest layer of the atmosphere,extending from the Earth's surface up to about $10-15 \ km$.
It is the region where most weather phenomena,including cloud formation,occur.
Since humans and other living organisms reside on the Earth's surface,we also live within the $Troposphere$.
Therefore,both cloud formation and human life occur in the $Troposphere$.

(A) Photochemical smog occurs in the presence of sunlight and has a high concentration of oxidising agents like $O_3$ and $NO_2$. Therefore,it is also known as oxidising smog.

(A) Photochemical smog is formed by the action of sunlight on nitrogen oxides ($NO$,$NO_2$) and hydrocarbons released from automobiles and factories.
These pollutants react in the presence of sunlight to produce secondary pollutants like ozone $(O_3)$,formaldehyde,acrolein,and peroxyacetyl nitrate $(PAN)$.
Therefore,the primary species responsible for its formation are $NO$,$NO_2$,$O_3$,and hydrocarbons.

(B) $NO_2$ and hydrocarbons are the primary precursors of photochemical smog. Nitrogen oxides $(NO_x)$ are released into the atmosphere by automobiles and factories,which then react with hydrocarbons in the presence of sunlight to form photochemical smog.

(A) The greenhouse gases absorb infrared rays and emit heat. This heat cannot escape from the atmosphere,resulting in the heating up of the Earth's surface,which leads to global warming and the greenhouse effect.

(D) Lead emitted from the vehicular exhausts is a harmful pollutant because it persists in the environment as dust for an indefinite time period.
It is a major air pollutant in urban areas.
Anaemia,weakness,kidney failure,and neurological disorders are the symptoms of lead poisoning in humans.
Children are more prone to lead poisoning than adults.
Hence,the correct answer is $Lead$.

(D) The biosphere is the global ecosystem composed of all living organisms and their interactions with the environment.
It encompasses all regions of the Earth that support life.
This includes the lithosphere (land),the hydrosphere (water),and the atmosphere (air).
Therefore,the biosphere is the zone where life exists,spanning across the lithosphere,hydrosphere,and atmosphere.

(A) The biosphere is the global ecosystem composed of living organisms (biota) and the non-living (abiotic) factors from which they derive energy and nutrients. It is the zone on Earth where life exists and where individuals interact with each other and their environment.

(B) $Coal$,fossil fuels,crude oil,natural gas,etc.,are all hydrocarbon fuels. These are called non-renewable sources of energy because they take millions of years to regenerate themselves. In contrast,water energy is renewable because it is regenerated by the water cycle. Also,wind energy and solar energy are renewable sources of energy since they can easily be replenished.

(A) Noosphere is a synonym of environment.
It is the sphere of human thought.
The noosphere is the third in a succession of phases of development of the Earth,after the geosphere (inanimate matter) and the biosphere (biological life).

(B) The living organisms on or around the earth constitute the $Biosphere$.
It is the global sum of all ecosystems.
It can also be termed as the zone of life on Earth,a closed system,and largely self-regulating.

(C) The biosphere is the global sum of all ecosystems. It can also be termed as the zone of life on Earth or the area occupied by living beings.

(B) The Earth's atmosphere is divided into layers based on temperature changes with altitude. Starting from the Earth's surface and moving upwards,the sequence is:
$1$. Troposphere ($0$ to $12 \ km$)
$2$. Stratosphere ($12$ to $50 \ km$)
$3$. Mesosphere ($50$ to $80 \ km$)
$4$. Thermosphere ($80$ to $700 \ km$)
$5$. Exosphere ($700$ to $10,000 \ km$)
Therefore,the correct sequence starting from the Earth's surface is Troposphere,Stratosphere,Mesosphere,and Thermosphere.

(D) The $Biosphere$ is the global ecological system integrating all living beings and their relationships,including their interaction with the elements of the lithosphere,geosphere,hydrosphere,and atmosphere.

(D) The biosphere is the global ecological system integrating all living beings and their relationships,including their interaction with the elements of the lithosphere,hydrosphere,and atmosphere.

(D) Checking atomic blasts will reduce radioactive pollution.
Sewage pollution can be prevented by treating sewage before passing it into water courses in a sewage treatment plant or effluent treatment plant $(ETP)$.
Electrically operated vehicles will control automobile exhaust and improve the air quality in cities.
Therefore,all the given methods are effective ways to control pollution.

(C) If water pollution continues at its present rate,it will eventually lead to the depletion of dissolved oxygen in water bodies. This makes oxygen molecules unavailable to water plants and aquatic animals,leading to their death. Pollutants often cause eutrophication,which consumes oxygen and disrupts the aquatic ecosystem.

(A) Acid rain is primarily caused by the emission of sulfur dioxide $(SO_2)$ and nitrogen oxides ($NO_x$,such as $NO_2$) into the atmosphere.
These gases react with water vapor,oxygen,and other chemicals in the presence of sunlight to form sulfuric acid $(H_2SO_4)$ and nitric acid $(HNO_3)$.
These acids then fall to the ground with precipitation,resulting in acid rain.

(C) Environmental pollution is defined as the undesirable change in physical,chemical and biological characteristics of our air,land and water.
As a result of over-population,rapid industrialization,and other human activities like agriculture and deforestation,the earth has become loaded with diverse pollutants that are released as by-products.
These changes are inherently undesirable and harmful to human life and other organisms.

(B) Motor vehicles are considered the greatest source of air pollution these days. As the population increases,the number of motor vehicles on the road also increases. These vehicles cause high emissions of $CO_2$,$CO$,$NO_x$,and particulate matter,which are major contributors to air pollution.

(A) Top soil is the vital part of the soil and serves as the chief source of nutrition for plants.
Loss or disturbance of top soil by natural agents like water,wind,gravity,or ice is called soil erosion.

(A) Acid rain is a form of precipitation that is unusually acidic,meaning it possesses elevated levels of hydrogen ions (low $pH$).
Acid rain is primarily caused by the emissions of sulfur dioxide $(SO_2)$ and nitrogen oxides $(NO_x)$,which react with water molecules in the atmosphere to produce acids.
The chemical reactions are as follows:
$2SO_2 + O_2 + 2H_2O \rightarrow 2H_2SO_4$
$4NO_2 + O_2 + 2H_2O \rightarrow 4HNO_3$
Among the given options,$SO_2$ is a primary contributor to acid rain.

(B) $CO_2$ is a greenhouse gas.
Greenhouse gases are responsible for trapping heat in the Earth's atmosphere.
The heat trapped helps in maintaining the temperature on the Earth.
However,an increase in the concentration of $CO_2$ will cause more heat to be trapped in the atmosphere.
As a result,the temperature of the Earth will increase,and this phenomenon is called global warming.
Therefore,option $B$ is correct.

(D) Plants perform photosynthesis,a process in which they absorb $CO_2$ from the atmosphere and release $O_2$ as a byproduct.
Therefore,planting more trees helps in reducing the concentration of $CO_2$ and increasing the concentration of $O_2$ in the air,which helps in mitigating global warming and maintaining the balance of gases in the atmosphere.

(D) Smog is a mixture of various pollutants.
Common components of photochemical smog include peroxyacetyl nitrate $(PAN)$,peroxybenzoyl nitrate $(PBN)$,nitrogen dioxide $(NO_2)$,and hydrogen peroxide $(H_2O_2)$.
Therefore,all the given options are components of smog.

(D) The ozone layer,composed of $O_3$ molecules,is present in the stratosphere.
It acts as a protective shield by absorbing the harmful $UV$ radiations coming from the sun.
Therefore,$O_3$ protects life on earth from the harmful effects of $UV$ radiation.

(B) Ozone is a gas found in the atmosphere made up of $3$ atoms of oxygen.
Ozone is formed in the atmosphere when energetic $UV$ radiation dissociates molecules of oxygen $(O_2)$ into separate oxygen atoms $(O)$.
These free oxygen atoms can recombine with oxygen molecules to form ozone $(O_3)$.
$O_2 + UV \rightarrow O + O$
$O + O_2 \rightarrow O_3$
Ozone molecules can also be decomposed by $UV$ radiation into a free atom and an oxygen molecule.
Thus,ozone is continuously created and destroyed in the atmosphere by $UV$ radiation coming from the sun.

(B) Oxygen enters the water through diffusion and water has the capacity to hold dissolved oxygen. When untreated sewage is discharged into water bodies,it is rich in organic matter. Microbes present in the water utilize the dissolved oxygen to decompose this organic matter,a process measured as Biological Oxygen Demand $(BOD)$. The higher the $BOD$,the lower the concentration of dissolved oxygen in the water. This depletion of oxygen leads to hypoxia in fish,causing them to die.

(A) Automobile exhaust contains various gases such as $CO$,$CO_2$,$NO_x$,and unburnt hydrocarbons.
Among these,$CO$ (carbon monoxide) is considered the most toxic and primary pollutant released from automobile exhaust due to incomplete combustion of fuel.
While $CO_2$ is present in large quantities,$CO$ is the most hazardous pollutant in terms of immediate health impact.

(D) Most of the ultraviolet radiation in sunlight is absorbed by the ozone layer,which is located in the stratosphere.
This ozone layer protects the Earth's surface from harmful $UV$ radiation.
Of the ultraviolet radiation that reaches the Earth's surface,almost $99$ percent is $UVA$ radiation.

(D) Global warming is the long-term rise in the average temperature of the Earth's climate system.
It leads to the melting of polar ice caps and glaciers,which causes a rise in sea levels,potentially leading to $flood$.
Changes in atmospheric temperature and pressure patterns can increase the frequency and intensity of extreme weather events like $cyclone$.
Additionally,shifts in climate patterns and increased temperatures can negatively impact ecosystems,leading to a $decrease in forest productivity$.
Therefore,all the mentioned consequences are potential results of global warming.

(A) $DDT$ and $BHC$ are chlorinated organic compounds that are known to be persistent environmental pollutants.
Scientific studies have indicated that these substances can act as carcinogens,as they have shown adverse effects on the liver and reproductive systems in laboratory animal studies.
Therefore,$DDT$ is classified as a possible human carcinogen.

(D) The statement that fishes grow equally well in warm and cold water is incorrect.
Most fish species have a specific temperature range within which they thrive.
Sudden changes in water temperature or extreme temperatures (too hot or too cold) can be fatal to aquatic life,as it affects their metabolic processes and oxygen solubility in water.

(D) The presence of $CFCs$ (chlorofluorocarbons) in the atmosphere is the primary cause of ozone layer depletion in the stratosphere.
$CFCs$ are released from refrigerators,air conditioners,and aerosol sprays.
In the stratosphere,$CFCs$ break down under $UV$ radiation to release chlorine radicals $(Cl^{\bullet})$,which catalyze the decomposition of ozone $(O_3)$ into oxygen $(O_2)$.
This depletion leads to the formation of an 'ozone hole',allowing harmful $UV$ radiation to reach the Earth's surface.

(C) Silicosis is a lung disease caused by the inhalation of dust containing silica.
Since cement plants and limestone quarries involve exposure to dust containing silica,lime,and alumina,workers in these environments are highly prone to developing $Silicosis$.

(A) $CO$ (carbon monoxide) is not a greenhouse gas because it does not absorb infrared $(IR)$ radiation effectively.
Greenhouse gases like $CH_4$,$O_3$,and $H_2O$ vapour trap heat in the atmosphere,whereas $CO$ does not contribute significantly to the greenhouse effect or global warming.

(C) The smog which is formed in the presence of sunlight is called photochemical smog.
This occurs in the months of summer when $NO_2$ and hydrocarbons are present in large amounts in the atmosphere.
Concentration of $O_3$,$PAN$,aldehydes,and ketones increases in the atmosphere.
$SO_2$ is not a component of photochemical smog; it is typically associated with classical (sulfurous) smog.

(A) Classical smog occurs in a cold and humid climate.
It is a mixture of smoke,fog,and $SO_2$.
It contains compounds of a reducing nature.
Option $A$ describes photochemical smog,which is produced by the action of sunlight on nitrogen oxides and hydrocarbons emitted by automobiles and factories.

(A) Clean water has a $BOD$ value of less than $5 \ ppm$.
If the $BOD$ value is equal to or more than $12 \ ppm$,the water is considered to be highly polluted.
Therefore,a $BOD$ value of less than $5 \ ppm$ indicates that the water is clean and rich in dissolved oxygen,which supports the survival of aquatic life.