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Environmental Chemistry

JEE Chemistry · 92 questions · Page 4 of 10 · Click an option or "Show Solution" to reveal answer

Q31
Which of the following is true about freons?
A These are radicals of chlorine and chlorine monoxide
B These are chemicals causing skin cancer
C All radicals are called freons
D These are chlorofluorocarbon compounds
Correct Answer
Option D
Solution

Freons are a family of chlorofluorocarbon (CFC) compounds, which are chemicals that contain chlorine, fluorine, and carbon atoms.

They are used in a variety of applications, including refrigeration and air conditioning, as well as in aerosol spray cans.

Q32
The correct set of species responsible for the photochemical smog is :
A NO, NO2, O3 and hydrocarbons
B N2, NO2 and hydrocarbons
C CO2, NO2, SO2 and hydrocarbons
D N2, O2, O3 and hydrocarbons
Correct Answer
Option A
Solution

Photochemical smog contains oxides of nitrogen, ozone and hydrocarbons.

Q33
The conversion of hydroxyapatite occurs due to presence of F−- ions in water. The correct formula of hydroxyapatite is :
A [3Ca3(PO4)2 . Ca(OH)2]
B [3Ca(OH)2 . CaF2]
C [Ca3(PO4)2 . CaF2]
D [3Ca3(PO4)2 . CaF2]
Correct Answer
Option A
Solution

The F

Θ\Theta

ions make the enamel on teeth much harder by converting hydroxyapatite, [3Ca3(PO4)2] .

Ca(OH)2], the enamel on the surface of the teeth into much harder fluroappatite.

[3Ca3(PO4)2 .

CaF2]

Q34
The radical which mainly causes ozone depletion in the presence of UV radiations is :
A NO⋅\mathrm{NO}^\cdot
B CH3⋅\mathrm{CH}_{3} ^\cdot
C Cl˙\dot{\mathrm{Cl}}
D O˙H\dot{\mathrm{O}} \mathrm{H}
Correct Answer
Option C
Solution

The radical that mainly causes ozone depletion in the presence of UV radiation is Cl˙\dot{\mathrm{Cl}}.

The chloro radical reacts with ozone molecules to form chlorine monoxide and oxygen:

Cl˙+O3→ClO+O2\dot{\mathrm{Cl}} + \mathrm{O}_{3} \rightarrow \mathrm{ClO} + \mathrm{O}_{2}

This reaction depletes the ozone layer, as the chlorine monoxide can then go on to react with another ozone molecule:

ClO+O3→Cl+2O2\mathrm{ClO} + \mathrm{O}_{3} \rightarrow \mathrm{Cl} + \mathrm{2O}_{2}

Thus, Cl˙\dot{\mathrm{Cl}}, is the correct answer.

Q35
The possibility of photochemical smog formation will be minimum at :
A Mumbai in May
B Kolkata in October
C New-Delhi in August (Summer)
D Srinagar, Jammu and Kashmir in January
Correct Answer
Option D
Solution

The formation of photochemical smog depends on several factors, including sunlight, temperature, and the presence of pollutants such as nitrogen oxides and volatile organic compounds.

Option (A) Mumbai in May may also have some possibility of photochemical smog formation because the temperature and sunlight are relatively high in May.

Option (B) Kolkata in October may have some possibility of photochemical smog formation because the temperature and sunlight are still relatively high in October.

Option (C) New-Delhi in August (Summer) is more likely to have photochemical smog formation because the temperature and sunlight are at their peak in the summer months, and there is a high level of air pollution in the city due to various anthropogenic activities.

Option (D) Srinagar, Jammu and Kashmir in January is less likely to have photochemical smog formation because the winter season typically has less sunlight and lower temperatures, which are not conducive to the formation of photochemical smog.

Therefore, the answer is (D) Srinagar, Jammu and Kashmir in January, as it is the option with the least possibility of photochemical smog formation.

Q36
Water samples with BOD values of 4 ppm and 18 ppm, respectively are :
A Clean and Highly polluted
B Highly polluted and Clean
C Highly polluted and Highly polluted
D Clean and Clean
Correct Answer
Option A
Solution

Clean water would have BOD value of less than 5 ppm whereas highly polluted water could have a BOD value of 17 ppm or more.

Q37
Air pollution that occurs in sunlight is :
A oxidising smog
B reducing smog
C fog
D acid rain
Correct Answer
Option A
Solution

Air pollution caused by sunlight is photochemical smog and it is oxidising.

Q38
Given below are two Statements: Statement I : Classical smog occurs in cool humid climate. It is a reducing mixture of smoke, fog and sulphur dioxide. Statement II : Photochemical smog has components, ozone, nitric oxide, acrolein, formaldehyde, PAN etc. In the light of the above statements, choose the most appropriate answer from the options given below.
A Both Statement I and Statement II are correct.
B Both Statement I and Statement II are incorrect.
C Statement I is correct but Statement II is incorrect.
D Statement I is incorrect but Statement II is correct.
Correct Answer
Option A
Solution

(I) Classical smog occurs in cool humid climate.

It is a reducing mixture of smoke, fog and sulphur dioxide.

This is a correct statement.

(II) This statement is also based on fact and is a correct statement.

Q39
The smog is essentially caused by the presence of :
A O2 and O3c
B O3 and N2
C Oxides of sulphur and nitrogen
D O2 and N2
Correct Answer
Option C
Solution

Photochemical smog is caused by oxides of sulphur and nitrogen.

Q40
The incorrect statement(s) among (a) – (d) regarding acid rain is (are) : (a) It can corrode water pipes. (b) It can damage structures made up of stone. (c) It cannot cause respiratory ailments in animals. (d) It is not harmful for trees
A (c) and (d)
B (a), (b) and (d)
C (c) only
D (a), (c) and (d)
Correct Answer
Option A
Solution

(1) Acid rain corrodes water pipes resulting in the leaching of heavy of heavy metals such as iron, lead and copper into the drinking water.

(2) Acid rain damages buildings and other structures made of stone or metal.

(3) It causes respiratory aliments in human beings and animals.

(4) It is harmful for agriculture, trees and plants as it wasshes down the nutrients needed for its growth.

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