M A N ZI L

For JEE Aspirants Legend

O N E SHOT

ENVIRONMENTAL CHEMISTRY BY : MOHAN SIR

(CMS SIR)
TOPICS T O BE COVERED

1. EnvironmentalPollution

2. Atmospheric Pollution

3. Wa t e r P o l l u t i o n

Soil Pollution and Green Chemistry

 ENVIRONMENTAL POLLUTION:

> Undesirable changes that have harmful effects o n plants, animals and human
beings in our surrounding is called environmental Pollution.
 ENVIRONMENTAL POLLUTION:

Pollutant:

> The substance which causes pollution and is harmful for environment.
 ENVIRONMENTAL POLLUTION:

BIODEGRADABLE AND NON-BIODEGRADABLE POLLUTANTS :

> Those substances which are degraded rapidly by natural process or artificial
methods (radiation a n d microbial action) a r e called biodegradable pollutions.

> While those substances which degrade a t very slow rate or does not degrade
by natural biological process, for example, DDT, arsenic salts of heavy metals,
radioactive materials and plastics are non-biodegradable pollutions.
ATMOSPHERIC
POLLUTION
 ATMOSPHERIC POLLUTION :
→troposphere
→§toatosphere
> The lowest region of atmosphere i n which the human beings along with other
organisms live is called troposphere.

> I t extends up to the height of ~ 10 km from sea level.

> Above the troposphere, between 10 and 50 km above sea level lies stratosphere.
> Troposphere is a turbulent, dusty zone containing air, much water vapour and clouds.
This i s the region of strong air movement and cloud formation.

> The stratosphere, on the other hand, contains dinitrogen, dioxygen, ozone and little
w a t e r v a p o u r.

> Atmospheric pollution i s generally studied a s tropospheric and stratospheric

po llu tio n.
 TROPOSPHERIC POLLUTION

> Tropospheric pollution occurs due t o the presence o f undesirable solid o r

gaseous particles in t h e air.

> The following are the major gaseous and particulate pollutants present i n the
troposphere:

1 . Gaseous a i r pollutants: These are oxides of sulphur, nitrogen and

carbon, hydrogen sulphide, hydrocarbons, ozone and other oxidants.

2 . Particulate pollutants: These are dust, mist, fumes, smoke, smog etc.
 GASEOUS AIR POLLUTANTS

( a )Oxides o f Sulphur:
503
> Oxides o f sulphur are produced when sulphur containing fossil fuel i s burnt.
> The most common species, sulphur dioxide, is a gas that is poisonous to both animals
an d pl an ts .
> Uncatalysed oxidation of sulphur dioxide i s slow. However, the presence of particulate
matter in polluted air catalyses the oxidation of sulphur dioxide to sulphur trioxide.
2S02 (g) +02 (g) →2S03 (g) UnCataly fed
The reaction can also be promoted by ozone a n d hydrogen peroxide

> S02 (8) +03 (8) →SO (8) +02 (8)

SO, (8) +H,02 (I) - (H,SO,)(aq)
 GASEOUS AIR POLLUTANTS

(b) Oxides of Nitrogen:

#A f does not
t Normal etmp.olw temp. No and O
rea ct.
I n a n automobile engine, (at high temperature) when fossil fuel i s burnt, dinitrogen and
dioxygen combine to yield significant quantities of nitric oxide (NO) and nitrogen dioxide
(NOz).
1483K
N2 + 02 → 2 N O
1483K
2NO + 02 → 2NO-

Nojalso reacts with ozone ot give NOz:

NO +03 → N02 + 02 Hgih etmp:
> It is also produced when lightning strikes then N, and 02 combine ot form (No,). NOz
gives NO which serves as fertilizer.
 GASEOUS AIR POLLUTANTS

(c) Hydrocarbons:
CHA
> Mainly Produced naturally (e.g., marsh gas) a s well as due to incomplete combustion.

These are carcinogenic and causes irritation of mucous membrane, eyes.

They causes ageing, breakdown o f tissues, shedding o f flower, leaves a n d twigs i n
plants.
 GASEOUS AIR POLLUTANTS
C O

( d ) Oxides o f Carbon:
( i ) Carbon monoxide: СОг
I t is colourless, odourless gas.
> I t is produced by incomplete combustion of fuels, naturally it is produced by oceans
or b y decaying of organic matter by bacteria.

It is poisonous because it combines with haemoglobin to form 300 more times stable
carboxyhaemoglobin which reduces oxygen-carrying capacity of blood a n d results
into giddiness, headache, decreased vision, cardiovascular malfunction and asphyxia.
> Cigarette smoke also contains a lot of CO which induces premature birth deformed
babies and spontaneous abortions in pregnant women.
 GASEOUS AIR POLLUTANTS

(d) Oxides of Carbon:

(ii) C a r b o n dioxide:

> I t is produced naturally by volcanic eruptions, respiration.

> I t i s also produced by burning of fossil fuels. Increased level of CO, is

controlled by green plants during photosynthesis.

> It is greenhouse gas and responsible for global warming. It causes headache
nausea and asphyxiation.
 Gr een hou se effect and Global wa rm ing

> 75% of solar radiation is absorbed by earth surface and remaining is reflected
back.

> Some of which is absorbed by green house gases which increases temperature
of atmosphere is called green house effect.
妙Besides carbon dioxide, other greenhouse gases a r e methane, water
vapour, nitrous oxide, CFCs and ozone.
ImprO, Wearl Vapou,rC
H
A, N5O,CFCES d3.
Gr een hou se eff ect and Global wa rm ing
 Greenhouse effect and Global warming

Ef fec ts :

> The average global temperature will increase t o a level which may lead t o
melting of polar ice caps and flooding of low lying areas all over the earth.

> Increase i n t h e global temperature increases t h e incidence o f infectious

diseases like dengue, malaria, yellow fever, sleeping sickness etc.
 HNO3
Acid R a i n :

> Acid rain has pH less than 5.6. Oxides of sulphur, nitrogen and carbon are
acidic i n nature which dissolve in water and causes acid rain.

(i) H,0 +COz =H,CO3 Arid Rain → p< 5.6

1 +6
P( i ) SO2 += 02 +H20 → H2SO4 50, 15% →503130→150
5（
E）NO2+2 02+2 H20 - →HNO

> When these acids come to earth's surface along with rain then it is called acid
rain.
Acid Rain :

Sulphuric acid (H25O4)

Nitric acid (HNOz)

0 0 0.0
‹Dry fallout Acid snow

Water vapour
(cloud) Acid rain

Acid fog
Sulphur dioxide
and
nitrogen dioxide
emission
Damage to
vegetation

Aquatic life in danger

 A ci d R a i n : CaCOz
Ta j Mahal a n d Acid r a i n :

> High level o f sulphur and nitrogen oxides caused b y combustion o f kerosene. p o o r
quality coal and firewood causes acid rain which reacts with marble and causes
discolouring and disfiguring.
CaCO3 +H , S O CaSO +H,0 +CO2
> Therefore, i n order t o save Taj, area including Mathura, Firozabad, Agra and
Bharatpur called Taj trapezium is/switched over to use of natural gas or LPG in
ind ust ries .

> People are also encouraged to use LPG as fuel.

vehicles are encouraged to use low-sulphur content diesel.

 PARTICULATE POLLUTANTS:

> Minute solid particles o r liquid droplets i n air that cause pollution a r e called
particulate pollutants.

Types: Viable and Non-viable:

(Viable) These are living organism like bacteria, fungi, moulds, algae etc.
> Non-viable:

( i ) Smoke from combustion of oil, fossil fuel, cigarette, dry leaves, garbage consists
of solid or mixture of solid and liquid particles.

(ii) Dust are particles from sand blasting wood works, pulverizing coal, ash o f
factories, dust storm, size is over 1um in diameter:
 PARTICULATE POLLUTANTS:

(iii) Mist is obtained from condensation of vapours of spray liquids.

(iv) Fumes are obtained from condensation of vapours from boiling, distillation,
sublimation e t c .

Particulate having size less t h a n 5 microns enter i n lungs while bigger than
5microns lodge in nasal passage.
 Smog: smoke +Fog clappical →Co
ol u
hmi
d diate,
→ Smoke, Fag +50g
> The word smog is derived from smoke and fog.
> There are two types of smog:
→Reducing smog
( a ) Classical smog occurs in cool humid climate. It is a mixture of smoke, fog and sulphur
dioxide.
• Chemica lly i t i s a r e d u c i n g m i x t u r e a n d s o i t i s a l s o called a s r e d u c i n g s m o g .

(b) Photochemical smog occurs in warm, dry and sunny climate.

→ O X I d I S i N a SMO
R
• T h e m a i n components o f t h e photochemical s m o g result f r o m t h e action o f sunlight o n
unsaturated hydrocarbons and nitrogen oxides produced by automobiles and factories.
> Photochemical smog h a s high concentration of oxidising agents and is, therefore, called a s
oxidising smog.
 Smog:

FORMATION OF PHOTOCHEMICAL SMOG :

> On burning fossils, hydrocarbons and nitric oxides are produced. NO converts into NOz and in
preseree NO, on reaction sunlight it gives NO and free oxygen. This free oxygen forms 03 with
02 and this 03 reacts with NO.
2NO(g) + g ⼀ 2N02 (g)

N02 ( g) No(s) +O= free orygent

0(g) + 02(g) = 03(g)
NO(g) +O3(g) →NOz(g) +0z(g)
 Smog:

FORMATION OF PHOTOCHEMICAL SMOG :

> Ozone is a toxic gas and both NO, and 03 are strong oxidising agents and can
react w i
th h
te unburnt hyd r
o car
b onsni the po luted ai
r ot pr
o
such as formaldehyde, acrolein and peroxyacetyl nitrate (PAN).
duc
e chemi
c al
s
C150 N o
3СН, +203 →3CHz =0 +3H,0 Formaldehyde
A

0
CH2=CHCH=0 Acrolein
CH
CAC
/ OONO, Peroxyacetyl nitrate (PAN) 2 -
CH3-C-O-0-NO2
H COOONO
C
 STRATOSPHERIC POLLUTION:

O z o n e Formation a n d i t s B r e a k d o w n
2
> Molecular oxygen splits into f r e e oxygen atom b y UV radiations which
combine with molecular oxygen t o for m ozone. B • 0 . = 1.5

02(g) "V,>0(gU V) + 0(g) 0 =0

Forward →endoth
0(g) + 02(g) = 03 (g) → BarkWards ero
ermic
thermid
decomposition)
• A s o z o n e i s the rmo dyn ami call y l u n s t a b l e h e n c e , t h e r e e x i s t s dynamic
equilibrium between its decomposition and formation.
 STRATOSPHERIC POLLUTION:

O z o n e Formation a n d i t s B r e a k d o w n

> Ultravio let r a d i a t i o n s d i s s o c i a t e chlorofl uorocarb on t o give c h l o r i n e - f r e e

radical, which combines with ozone to form chlorine monoxide radical which
combines with f r e e oxygen to f orm c a n b e given a s
CF2 C12 →CF2 Cl + Cl CF, C 2 CECi
C
1 +03 - C1O +02
2C10 +03 →2C1 +202
> These chlorine radicals deplete ozone layer. 2010+03→201+702
 STRATOSPHERIC POLLUTION:

O z o n e Hole :

> In winter, special type of clouds called polar stratospheric clouds are formed over
Antarctica. These polar stratospheric clouds provide surface o n which chlorine
nitrate formed gets hydrolysed to form hypochlorous acid.
- H0
> It also reacts with hydrogen chloride produced to give molecular chlorine.
ClO(g) +NO,(g) → CIONO, (g)
C|(g) +CH,(g) → CH:(g) +HCl(g)
CIONO2 (g) + H20(g) →HOC(g) +HN03(g)
CIONO ( g ) + HGIg) → Cl, (g) + HNO3 (g)
 STRATOSPHERIC POLLUTION:

O z o n eH o l e:

In spring season, sunlight breaks HOCl and Cl, to give chlorine redicals.
HOCI(g) — →OH(g) + Cl(g)

Cl, (g) →> 2C1(g)

These chlorine-free radicals deplete ozone layer.
WAT E RPOLLUTION
 WATER POLLUTION:

> Any unwanted change which detiorate quality of water and make i t unfit for
drinking.

> Pollution sources are of two types.

Point Sources: Involve discharge from identifiable points e.g., discharge of

w as te w at er fr o m factory.
> Non-Point sources: Involve discharge from unidentifiable points. I t
includes discharge from land r u n off, atmosphere washout etc.
 CAUSES OF WATER POLLUTION:

( i ) Pathogens:

> The most serious water pollutants are t h e disease causing agents called pathogens.
Pathogens include bacteria and other organisms that enter water from domestic
sew age a n d ani ma l exc reta .
(ii) Organic wastes: #D0 Sop
> 10ppm
Bl
a d
> The other major water pollutant is organic matter such as leaves, grass, trash etc.
> The large population of bacteria decomposes organic matter present in water. They
consume oxygen dissolved in water.
DO →(oppm-loppm) ok
I n cold water, dissolved oxygen (DO) c a n r e a c h a concentration u p t o 1 0 p p m (parts
per million), whereas oxygen in air is about 200,000 ppm.
 CAUSES OF WATER POLLUTION:

Pollutant Source
Mic ro-o rga nism s > Domestic sewage
Organic wastes Domestic sewage, animal excreta and waste, decaying animals
and plants, discharge from food processing factories.
Plant nutrients Chemcial fertilizers
Toxic heavy metals ›Industries and chemical factories
Sediments Erosion of soil by agriculture a n d strip mining
Pesticides Chemicals used for killing insects, fungi and weeds
Radioactive s u b s t a n c e s Mining of uranium containing minerals
Heat Water used for cooling in industries
 CAUSES OF WATER POLLUTION:
> If too much of organic matter is added to water, all the available oxygen is used up. This causes
oxygen dependent aquatic life to die.

> Thus, anaerobic bacteria (which d o not require oxygen) begin t o break down the organic
waste and produce chemicals that have a foul smell and are harmful to human health.

> Aerobic (oxygen requiring) bacteria degrade these organic wastes a n d keep t h e water
depleted i n dissolved oxygen clean water →BoD<5ppm
V. v.Imp P el l ti nD BoD≥n- H i
g hl
y P oluted
Thus, the amount of oxygen required by bacteria to break down the organic matter present in
a certain volume of a sample of water, is called Biochemical Oxygen Demand (BOD).

> Clean water would have B

OD value of less than 5ppm whereas highly polluted water could
have a BOD value of 17 ppm or more.
 CAUSES OF WATER POLLUTION:

(iii) Chemical pollutants:

> These a r e of two types, inorganic and organic.

> Inorganic pollutants constitute acids, salts, heavy metals such as Cd, Hg, Ni etc. Heavy
metals damage central nervous system, liver and kidneys.

› Organic pollutants constitute, pesticides, petroleum pollutants, PCBs, detergents,

fertilizersetc.

> P C Polychlorinated Biphenyls) a r e carcinogenic and phosphatic fertilizers increase

algae growth. Acidic (Polychlorinated Biphenyls) a r e carcinogenic and phosphatic
fertilizers increase algae growth. Acidic water is harmful for aquatic life as well as
for drinking.
> Eutrophication ETellition
 CAUSES OF WATER POLLUTION:
INTERNATIONAL STANDARDS FOR DRINKING WATER
S.No. Chem ical Tolerable limit Effects
Nitrates 50 ppm nI excess, it causes blue-baby syndrome
1

2. Fluoride 1 ppm In excess, it is poisonous and harmful for bones

and t e e t h
3. Sulphates 500 ppm In excess, it causes laxative effect
Lead (Pb) 50 ppb In excess, it damages kidney, brain and liver
4

Metal Maximum concentration

(ppm or mg dm")
Fe 0.2
Mn 0.05
Al 0.2
Cu 3.0
Zn 5. 0
Cd 0.005
 CAUSES OF WATER POLLUTION :

> T h e F i o n s m a k e t h e e n a m e l o n t e e t h m u c h h a r d e r b y convertin g
hydroxyapatite, [3 (Cag(PO, )z Ca(OH), ] , the enamel on the surface of the
teeth, into much harder fluorapatite, [3 (Caz(PO)2-CaF 2I-
S O I LP O L L U T I O N
 SOIL POLLUTION:

> I t is unfavourable alteration of soil b y addition o r removal of substances and factors

which decrease soil productivity, quality of plants and ground water is called soil
polluti on.

> Mainly caused by chemicals added into soil as pesticides, herbicides and fertilizers
for batter productivity.

> These chemicals reached in human beings through food chain and causes harmful
effects.
 SOIL POLLUTION:

Pesticides:
> These a r e actually synthetic toxic chemicals w i t h ecological repercussions. These a r e
used in killing pathogens, pests and in inhibiting unwanted growth in agriculture,
horticulture, forestry and water.
李Organochlorines are persistent insecticides which show biological magnification e.g.
> DDT, BHC, Aldrin, Endrin, Dieldrin etc.

> These are water insoluble, non-biodegradable, hence get transferred from lower level
to higher level in food chain.
> Carbamates and organophosphates are less persistent and more biodegradable a r e
n e r v etoxins.

> Insects also becomes resistant to particular pesticides after successive use.
 SOIL POLLUTION:

Herbicides: N9C103 →Nag1503

e use herbicidesni place ofpesticides. Herbicides are generally
>Now adays w
metabolic inhibitors e.g., sodium chlorate, sodium arsinite and may other.
> These decompose in few months and not very much persistent.
> Arsenic-containing herbicides a r e harmful t o mammals. Some herbicides
cause birth defect also.
 INDUSTRIAL WASTE

Industrial wastes are both solid and liquid and a r e dumped over t h e soil. These
contain toxic chemical like mercury, copper, zinc, lead, cadmium, cyanides, acid,
alkalies etc.
> Biodegradable: Includes wastes by cotton mills, food processing units, paper
mills, textile factories etc.
> Non-biodegradable: Gypsum from fertilizer industries, mud a n d taillings
from metal industries, slag from steel industries, fly ash from thermal power
p l a n t setc.
 STRATEGIES TO CONTROL ENVIRONMENTAL POLLUTION:

> Waste Management

> Collection and Disposal

G R E E N C H E M I S T RY
 GREEN CHEMISTRY :

Green chemistry i s a w a y o f thinking a n d i s a b o u t utilising t h e existing

knowledge and principles of chemistry and other sciences to reduce the adverse
impact o n environment.

Green chemistry i s a production process t h a t would bring a b o u t minimum

pollution or deterioration to the environment.
 Green Chemistry in day to day life :

( i ) Dry Cleaning of Clothes :

> Tetra chiroroethene (Cl,C=CCl) was earlier used a s solvent for dry cleaning. The
compound contaminates the ground water and is also a suspected carcinogen.
> These days hydrogen peroxide (H,02) is used for the purpose of bleaching clothes in
t h e process of laundary, which gives better results and makes use of lesser amount o f
w a t e r.

(ii) Bleaching of Paper:

> Chlorine gas was used earlier for bleaching paper. These days, hydrogen peroxide
(H,0z ) with suitable catalyst, which promotes the bleaching action of hydrogen
peroxide, is used
 Green Chemistry in day to day life :

(iv) 'Green Solution' t o Clean Turbi d Wate r

› Powder of kernel of tamarind seeds h a s b e e n found t o b e a n effective material
t o m a k e municipal a n d industrial waste water clean. I t i s non-toxic,
biodegradable and cost effective material.
 T h e pollution d u e t o o x i d e s o f Sulphur g e t s e n h a n c e d d u e t o t h e
p r e s e n c eof: [NEET - 2 0 2 2 ]
1 .Particularm a t t e r
00-503
2 .O z o n e
3 .Hydrocarbons
5
4 . Hydrogen peroxide
Choose the most appropriate answer from the options given below:

A 1, 3, 4only 1 , 4 only

1, 2, 4 only 2 , 3, 4 only
A student collected samples from two water b o d i e s Aa n d B in a m e t r o
city. The biochemical oxygen demand for 'A' is 3 p p m while for B i s
found t o b e 1 8 ppm. Which o n e of t h e following is t r u e ?
[NEET - 2 0 2 2 ]

Both A a n d B a r e c l e a n Both Aand Bare polluted

A is clean but B is polluted Ais polluted but Bis clear

Ans. (C)
M a t c hL i s t- I w i tL i s t- I I [NEET - 2 0 2 2 ]

List- I L i s t- I I
(1) Biochemical smog ( i ) Oxidising mixture
(2) Photochemical s m o g (ii) P o l a r stratospheric cloud
(3) Classical smog (iii) Reducing mixture
(4) Ozone layer depletion (iv) Reducing mixture
Choose t h e correct a n s w e r f r o m t h e options given below:

1 2 3 4 1 2 3 4
iii iii iv I ii

iii i v i v iii ii i

Ans. (C)
 Which of the following is not correct about carbon monoxide?
[NEET - 2 0 2 0 ]

(A) It forms carboxyhaemoglobin.

B I t reduces oxygen carrying ability of blood.

oxyhaemoglobin.

I t is produced due to incomplete combustion.

Ans. (C)
 Among t h e following, t h e o n e that i s n o t a green house gas i s
[NEET - 2 0 1 9 ]

sulphur dioxide n i t r o u s oxide

methane ozone

Ans. (A)
 W h i c h o n e o f t h e following i s n o t a c o m m o n c o m p o n e n t o f
photochemical smog?

A Ozone Acrolein
0O
- ND2
CM3-§-
Peroxyacetyl nitrate
Chlorofluorocarbon/

Ans. ( D )
 Which o n e of t h e following statements regarding photochemical smog
i sn o tcorrect? [2012 ]

Carbon monoxide does n o t play any role i n photochemical smog formation.

Photochemical smog is an oxidising agent in character.

Photochemical s m o g i s formed through photochemical reaction involving

s o l a r ene rgy .

Photochemical smog does n o t cause irritation in eyes and throat.

Ans. ( D )
Which o n e o f t h e following i s responsible f o r depletion o f t h e o z o n e
layer in the upper strata of the atmosphere?

Pol yha loge ns Ferrocene

Fullerenes Freons

Ans. ( D )
 About 20 km above the earth, there is a n ozone layer. Which one of the
following s t a t e m e n t s a b o u t ozone a n d o z o n e l a y e r i s t r u e ? [1995]

I t i s beneficial t o us a s i t stops U.V. radiation. Оз

Conversion of Oz to 02 is an endothermic reaction. 115
Ozone i s a triato mic linea r mole cule.

I t is harmful a s it stops useful radiation.

Ans. (A)
 Which o n e of t h e following statements i s n o t t r u e ? [NEET 2 0 1 3 ]

Clean water would have a BOD value of 5ppm.

Fluoride deficiency in drinking water is harmful. Soluble fluoride i s often u s e d

to bring its concentration upto 1ppm. 6
When hte pit forain waetr si hgiher htan 65., tisi caeld
acdi rain.
Dissolved Oxygen (DO) in cold water can reach a concentration upto 10ppm.

Ans. (C)
 Which of the following statement is NOT true about acid rain?
[NEET - 2 0 2 0 ]

It is due to reaction of SO,, NO, and CO, with rain water

Causes on damage ot monuments like Taj Mahay

I t is harmful to plants.

Its pH is less than 5.6

Ans. ( B )
 Which of the following are "green house gases"?
( a ) CO2 (b)02 (0) 0 3
( d ) CFC ( e )H , 0 '
C44 [JEE Main 2020, 8 Jan Morningl
a, band d
a, b,cand d
a,c a n dd

a , c, d and e
 Biochemical oxygen dema nd (BOD) is defined as ............ in ppm of 02-
[JEE Main 2020, 9 Jan Eveningl

Required to sustain life y

The amount o f oxygen required b y bacteria t o break d o w n t h e organic m a t t e r
present i n a certain volume o f a sample o f water.

he am o unt f
o o xygn
e re qu r
ied by anaeo
r bc
i b ace
tra
i t
o be
rak o
dwn the
T
inorganic matter present in a certain volume of a sample of water.

Required photochemical reaction to degrade waste.

 Thestatementthati sn o tt r u ea b o u tozonei s

[JEE Main 2020, 2 Sep. Morning]

In the stratosphere, CFCs release chlorine free radicals (CI) which reacts with
O3 to give chlorine dioxide radicals
ci t 9 - 2G0t
I t is a toxic gas and its reaction with NO gives NO,

I n the atmosphere, it is depleted by CFCs'

In the stratosphere, it forms aprotective shield against V

U ra d ia ti o n
 Thermal power plants can l e a d t o
[JEE Main 2020, 3 Sep. Morning]

Eutrophication X
Ozone alyer depletion y
Blue baby syndrome

Acidic r a i n
 The incorrect statements) among (a) - (d) regarding acid rain is (are)
( a ) I t c a n corrode water pipes.
( b ) I t c a n damage structures m a d e u p o f stone.
(c) It cannot cause respiratory ailments in animals. X
( d ) I t i s n o t harmful f o r t r e e s .
[JEE Main 2020, 3 Sep. Evening]

() and (d)
(a). C
( a ) , (b) a n d (d)

( c ) and (d)

(c) only
 The condition that indicates a polluted environment i s
[JEE Main 2020, 5 Sep. Morning]

0.03% of CO, in the atmosphere

p H of rain water to be 5.6

eutrophicat ion X

BOD value of 5 ppm

 The presence o f soluble fluoride i o n u p t o 1 p p m concentration i n
drinking water, i s
[JEE Main 2020, 6 Sep. Morning]
A safe for teth
B harmfulot skin X
harmful ofr teti
harmfulot bones
 The gas released during anaerobic degradation of vegetation may lead
to:
[JEE Main 2021, 24 Feb. Morning]
Global warming and cancer

B Acid rain A

Corrosion of metals
Ozoneh o l e
 Givenb e l o wa r et w os t a t e m e n t s :
Statement I: The value of the parameter "Biochemieal Oxygen Demand
(BOD)" is important for survival of aquatic life .
Statement II: The o p t i m u m value o f BOD i s 6 . 5 p p m .
I n t h e l i g h t o f t h e above statements, choose t h e m o s t appropriate
answer from t h e options given below.
[JEE Main 2021, 24 Feb. Evening]

Boht statement 1and Statement I are faloe

® Statemenel si false but Statement Isi true
S t a t e m e n t I i s t r u e b u t Statement I l i s f a l s e

B o t h S t a t e m e n t I a n d S t a t e m e n t II a r e t r u e
 Givenb e l o wa r et w os t a t e m e n t s : smokerfog t50
Statement-l: An allotrope of ox
t h e formation of reducing smog.
ygen is an important intermediate in
Statement-II: Gases such a s oxides o f nitrogen and sulphur present i n
tropospher e contribute t o t h e formation o f photochemical smog. I n
the light of the above statements, choose the correct answer from the
options given below:
[JEE Main 2021, 2 5 Feb. Morning]

Satetment and Satetment t ear true,

B o t h S t a t e m e n t I a n d S t a t e m e n t II a r e f a l s e

S t a t e m e n t I i s f a l s e b u t S t a t e m e n t II i s t r u e
 Givenb e l o wa r et w os t a t e m e n t s : W

Statement I : The p H o f rain water is normally ~ 5 . 6 .

Statement II: If the pH of rain water drops below 5.6, i t is called acid
rain.
I n the light of the above statements, choose t h e correct answer from
the option given below.
[JEE Main 2021, 2 5 Feb. Evening]

Statement is false but Statement I si true

Both statement I a n d statement I l are t r u

Both statement I a n d statement I l are false

S t a t e m e n t I i s t r u e b u t s t a t e m e n t II i s f a l s e
 The type o f pollution that gets increased during t h e day time and i n
the presence of 03 is: Sunny cau
JEEM a i n2 0 2 1 ,1 6MarchMorning]

Reducing smog X N1037 NO2

O
Oxidising smog

Global warming
Acid rain difficial
 The green h o u s e gas/es i s (are):
( a ) C a r b o n dioxide v [JEE Main 2021, 1 6 March Eveningl
(b) Oxygen \
( c ) Wa t e r v a p o u r
(d)M e t h a n e
Choose the most appropriate answer from the options given below:
(a) and (c) only

a only

(a), (c) and (d) only

D ( a ) and ( b ) only
 educing smog is a mixture of:
usmoket ofg +500 [JEE Main 2021, 17 March Morningl

X
Smoke, fog and O
Smoke, fog and SO2

Smoke, fog and CH2 =CH - CHO

Smoke, fog and N203

 Which o f t h e following statements) i s (are) incorrect r e a s o n f o r
eutrophication?
( a ) excess u s a g e of f e r t i l i s e r s
(b) excess usage of detergents
( c ) d e n s e plant population i n water b o d i e s
(d) lack of nutrients ni water bodies that prevent plant growth
Choose t h e most appropriate answer from t h e options given below:
[JEE Main 2021, 17 March Eveningl
(a) onyl X
B
(e) Only
(b) and (a) onyl
(d) only
 T h es t a t e m e n t t h a ta r eTRUE:
( a ) Methane leads t o b o t h global warming and photochemical smog
(b) Methane is generated from paddy f i e l d s
( c ) M e t h a n e i s a s t r o n g e r global warming gas t h a n CO≥
(d) Methane i s a p a r t of reducing smog →→ Sm k
oe
Choose the most appropriate answer from the options given below:
t fogt
[JEE Main 2021, 1 8 March Morningl
(a), (b), (c) only

B ( a ) and ( b ) only

(b), (c), (d) onlyd

(a), o() (al) onse
 Givenb e l o wa r et w os t a t e m e n t s :
Statement I : Non-biodegradable wastes a r e generated b y t h e t h e r m a l
powerplants.
Statement II: Bio-degradable detergents leads t o eutrophication.
I n t h e light o f t h e above statements, Choose t h e most appropriate
answer from the option given below
[JEE Main 2021, 1 8 March Eveningl
B o t hs t a t e m e n tI a n ds t a t e m e n tI Ia r ef a l s e
X
StatementI i st r u eb u tstatementIli sf a l s e
X
Statement is falfe but statement llsi true
Both satetment and statement l aer true
 Some gases a r e responsible f o r heating of atmosphere (green house
effect). Identify from t h e following t h e gaseous species which does n o t
c a u s ei t . [JEE Main 2022, 2 4 June Evening]

CHA

H,0
 The eutrophication of water body results i n :
[JEE Main 2022, 2 5 June Morning]

l o s s of Biodiversity

breakdown of organic matter X

meresni biodiverstay
d e c r e a s e i n BOD

increase
 Givenb e l o wa r et w os t a t e m e n t s :o n ei sl a b e l l e da sAssertionAa n dt h e
o t h e ri sl a b e l l e da sR e a s o nR
Assertion A:Polluted water may have a value of BOD of the order of 1 7
ppm.

R eason R: O
BD is a measure of oxygen required to oxid ise both the
biodegradable and non-biodegradable organic material in water.
I n t h e l i g h t o f t h e above statements, choose t h e most appropriate
a n s w e r f r o m t h e options given below: [JEE Main 2022, 2 5 June Evening]
e t h Anad Raer cometnad Rsihet corect espalnaoitn ora
o och Aand Raer corect butRsi T
ONhte corect expalnaoitn ofA
.
A i s correct b u t R i s n o t correct.

A is n o t correct b u t R i s correct.
 Givenbelowa r etwo statements:
Statement I : Classica, smog occurs i n cool humid climate. I t i s a
reducing mixture of smoke, fog and sulphur dioxide.
Statement II: Photochemical s m o g h a s components, ozone, nitric
oxide, acrolein, formaldehyde, PAN etc.
In the light of above statements, choose the most appropriate answer
f r o m t h e options given below: [JEE Main 2022, 27 June Morningl
Both S t a t e m e n t I a n d S t a t e m e n t I l a r e c o r r e c t

B B o t h S t a t e m e n t I a n d S t a t e m e n t II a r e i n c o r r e c t

Statement I is correct b u t statement I l i s incorrect

Statement I is incorrect b u t Statement I l is c o r r e c t

 Which amongst the following is n o t a pesticide?
[JEE Main 2022, 2 8 June Morning]

DDT
Na, 1503
B O rg a n o p h o s p h a t e s
NaClos
Dieldrin

S o d i u marsenite
 Correct statement about photo-chemical smog is:
[JEE Main 2022, 28 June Evening]

It occurs in humid climate.

B I samisture ofsmoke,oj and 50,/

it si reducing smo: y
rf reacoitn founsaturated hydrocarbons.
i t resultsom
 Sulphur dioxide i s one of the components of polluted air. SO, is also a
major contribu tor t o a c i d r a i n . The correct a n d complet e reaction t o
represent acid rain caused by SO, is:
[JEE Main 2022, 29 June Eveningl
250, +02 →2503 X
502 +0
3 →503 +02 Y
SO, +H20, →HS
,O,
2S02 + 02 + 2H,0 →2H,S04
 The photochemical smog does not generally contain:
[JEE Main 2022, 25 July Morningl

N O

B NO,

SO.
 Match L i s t I w i t h List I I .
List I ( P o l l u t a n t ) List I l ( S o u r c e )
A . Microorganisms St rip mi ni ng
B . P l a n tn u t r i e n t s• T .z Domesticsewage
C . Toxic heavy m e t a l s 出 C h e m i c a lfertilizer
D .Sediment Chemical factory
I V.
Choose t h e correct answer from t h e options given below:
[JEE Main 2022, 2 6 July Eveningl

A-II, B-1, C-IV, D-III

A-1, V-IV,C-I, D
N
I-K
-
A-1, B-IV,C-III, DN
 - 1oppr
Givenb e l o wa r et w os t a t e m e n t s : → 6
yStatement I : I n polluted water values of b o t h dissolved oxygen and
BOD a r e v e r y low.
iotatement I I : Eutrophication r e s u l t s i n decrease i n t h e a m o u n t o f
dissolved oxygen.
I n t h e light o f t h e above statements, choose t h e most appropriate
answer from t h e options given below:
[JEE Main 2022, 2 8 July Morning]
Both statement Iand statement Il are trivel

Boht satetment and satetment l ear false

Statement is the but statement il si false
Statement is false but statement Ilsi t r u e
 Which among the following pairs has only herbicides?
pesticide [JEE Main 2022, 29 July Morning]

Aldrin and Dieldrin Y

Sodium chlorate and Aldrie
Soduim arsinate and Dieldrin
Sodium chlorate a n d sodium arsinite
 Which of the following is true about freons?
[JEE Main 2023, 2 4 Jan. Morning]

T h e s e are chlorofluorocarbon compounds

These are chemicals causing skin cancer y

These r
e
a radc
ias
l o
f cho
lrn
ie d
a
n h
co
lrn
ie mn
ooi
d
xo
Allradical aer caeld freaks
 C o r r e c ts t a t e m e n ti s :
[JEE Main 2023, 2 4 Jan. Eveningl

n average human being consumes moer food than airy

A
A n average human being consumes nearly51times moer air htan food
nAaverage human being consumes equal amount offood and airy
A n average human being consumes 100 times more air htan food,
 Co rre ct sta tem ent ab ou t sm og i s
[JEE Main 2023, 29 Jan. Morning]

No,si presentni classical smos

Both NO,and SO, are presentni classical smog
Photochemical smog has high concentration of oxidizing agents

Classical smog also has high concentration of oxidizing agents

 The concentration o f dissolved Oxygen i n water f o r growth o f fish
should b e more than Xppm and Biochemical Oxygen Demand in clean
water should b e less than Y ppm. X and Y in p p m are, respectively.
[JEE Main 2023, 29 Jan. Evening]
Y
6 5

4
Y
8
D <5ppm
B
O
X Y
4 15

1
 Formation o f photochemical s m o g involves t h e following reaction i n
which A, B a n d Ca r e respectively.
NO + 0
(ii) B + 02 →C. 0+02-03
(ii) A +C→ NO, + 02
Choose the correct answer from the options given below:

N&NO;
A)Yo,O 03 N
O +03 1 B
e Tha3,03Ja
n. Mo
r
nn
ig]
в Xo, N,0 &N
O
N,02 &03

NO, 0 &03
 The water quality of a pond was analysed and its BOD was found to b e
4 . The pond has [JEE Main 2023, 30 Jan. Evening]

Highly polluted water X

Waetr has hgih amount offluoride compounds

o veyr celan waetr
Slightly polluted water
 T h e n o r m a l r a i n w a t e r i s slightly a c i d i c a n d i t s p H v a l u e i s 5 . 6
becomes o f which o n e of t h e following?
[JEE Main 2023, 31 Jan. Evening]
CO2 +H,0 →H,CO3 < 56

p
0
2 +2H0
, →H
4 NO:
X HNO3 , H
as0
4N02 +
2502 +02 +2H,0 →2H,S0x
N,0, +H0, - 2HNO3 \
T h a n k Yo u !