Atmospheric Pollution Dalal Simplified Class-9 ICSE Chemistry

Chapter-8 Atmospheric Pollution by Dr Viraf J Dalal Middle School Chemistry Allied Publishers

Atmospheric Pollution Dalal Simplified Class-9 ICSE Chemistry Solutions Chapter-8. .We Provide Step by Step Answer of Exercise /Lesson -8 Atmospheric Pollution with Additional Questions , Previous Year Questions and Unit Test-8 of Dr Viraf J Dalal Middle School Chemistry Allied Publishers New Simplified Chemistry . Visit official Website CISCE for detail information about ICSE Board Class-9.

Atmospheric Pollution Dalal Simplified Class-9 ICSE Chemistry Solutions Chapter-8

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 Unit Test-8 

Previous Year Questions of Exe-Atmospheric Pollution Dalal Simplified Class-9 ICSE Chemistry 


Question 1.[2007]

Name any two natural sources of atmospheric pollution.
Two natural sources of atmospheric pollution:

  1. Decay of plants and animals.
  2. Disintegration of rocks and soil.

Question 2.

Name any two gases which are responsible for the formation of acid rain.
SO2 and NO2 are gases responsible for acid rain.

Question 3.

Explain the term ‘global warming’.


Global warming: If the percentage of ‘green house gases’ increase, then the surface temperature of earth rises. “The rise in average temperature of earth’s surface is called global warming.”


Question 1.

State two effects of ozone depletion.

Effects of ozone deletion:
  1. Ultra-violet rays which are harmful will not be stopped and will reach the earth.
  2. Many organic species necessary for life will be destroyed.


Question 1.

What is meant by the term ‘acid rain’. Give any two impacts of acid rain.

Acid rain:

Oxides of sulphur [SO,] and nitrogen [NO,] present air mix with water [or snow, fog etc.] and fall down on the earth resulting in acid rain.

Two impacts of acid rain:
  1. The water of lakes and rivers which is becoming acidic, may not support aquatic life.
    Acid rain damages the buildings and sculptural materials or marble, lime stone, slate, mortar etc.
  2. These materials become pitted and weakened mechanically.

Question 2.

State two ways by which global warming can be reduced.

Two ways to reduce global warming:
  1. We should plant more trees to increase the green cover.
  2. Minimise the use of automobiles.

Question 3.

State an advantage of using solar energy.
Solar energy is renewable source of energy and does not produce pollution.


Question 1.

Explain the methods of preventing acid rain.

Method of preventing acid rain:
  1. By using coal or oil – that has low sulphur content. This reduces the emission of oxides of sulphur and nitrogen responsible for acid rain.
  2. By using scrubbers a device that absorbs gaseous pollutants.

Question 2.

State an advantages of CNG [compressed natural gas].
Advantage of using CNG causes less (minimum) pollution. It does not contain lead and lower maintenance cost.

Question 3.

State how CFCs break ozone in the stratosphere.

Depletion of 03 (ozone) by CFCs:
CFC [CFCl3 ] is broken by UV of sunlight to produce [Cl] atom or free radical [Cl] which highiy reactive in the atomic form and forms C10[g] with O2

C l [g] + O3[g] → ClO[g] + O2[g] This depletes ozone.

CIO further produces more [Cl] free radical
Cl0[g] + O[g] → Cl[g]  O2[g] and destroys more of O3 and there by giving rise of ozone depletion.

Question 4.

Describe the methods of saving the ozone layer.

Method to protect ozone layer:

Ozone layer is protected by alternative products like HCFC [hydro chloro fluoro carbons]

Additional Questions of Atmospheric Pollution Dalal New Simplified Class-9 ICSE

Question 1.

State what is meant by the term ‘atmospheric pollution’. Name four gaseous atmospheric pollutants.
Atmospheric pollution : Conditions of air made unclean due to introduction of foreign elements to air so as to cause adverse effects on living organisms on earth” is called atmospheric pollution.
Four gaseous pollutants are:

  1. SO2, SO3
  2. NO, N02
  3. CO2, CO
  4. H2S

Question 2.

Explain the term ‘acid rain’.
State the two forms of deposition of acid rain with suitable examples of each form of deposition.
Acid rain: Oxides of sulphur [S02] and nitrogen [N02] present air mix with water [or snow, fog etc.] and fall down on the earth resulting in acid rain.
Two forms are:

Ans 2 Additional Questions Atmospheric Pollution Dalal Simplified Class-9 ICSE

Question 3.

State the natural and man-made sources of the two pollutants responsible for acid rain.
Natural sources are:

  1. Volcanic eruptions
  2. Forests fires

Man made sources are:

  1. Automobile exhaust
  2. Industrial plants

Question 4.

Burning of fossil fuels is an important source of the pollutant – ‘oxides of sulphur’ responsible for acid rain.
State what are ‘fossil fuels’. Name the principal fossil fuels. State why sulphur dioxide is emitted on burning a fossil fuel. Give a balanced equation for the same.
Fossil fuels:
 “Fuels obtained from fossils i.e. organic remains of plants and animals.” Principal fossil fuels : coal, petroleum [oil] and natural gas.
On burning fossil fuels → SO, is produced from sulphur impurities present in coal.

Question 5.

During metallurgy – smelting plants produce sulphur dioxide, when metallic sulphides are roasted in air. Give a balanced equation for the same.
When sulphide ores are roasted in smelting plants SO2 is produced:
2ZnS + 3O2 → 2ZnO + 2SO2

Question 6.

State why high temperatures in internal combustion engines release pollutant – oxides of nitrogen.
In internal combustion engines combustion occurs with air drawn in. Air in a combustion chamber and this air drawn from the atmosphere contains 80% nitrogen.The nitrogen combines with oxygen at high temperature producing oxides of nitrogen.
N2 + O2 → 2NO [at high temp.]

Question 7.

State why natural rain water produced in an unpolluted atmosphere is slightly acidic. Give a balanced equation of the same.
Natural rain water is slightly acidic “as CO2 present in traces in unpolluted air dissolves in rain water forming weak carbonic acid [H2CO3].

Question 8.

Give balanced equations for the formation of sulphuric acid in acid rain, when’ a fossil fuel is burnt in an electric power station.
In electric power stations: When coal burns, S present in coal forms
SOS + O2 → SO2
SO2 as pollutant in air forms SO3
2SO2 + O2 → 2SO3
This SO3 comes in contact with water vapour present in air to form H2S04 and falls down as acid rain.

Question 9.

Starting from nitrogen in air, enlist the reactions with the help of balanced equations, which result in the conversion of nitrogen in an internal combustion- engine, to the acids formed which are responsible for acid rain.
In the internal combustion engine atmospheric air containing 80% N2 is used for combustion of fossil fuel.
At high temp. N2 + O2 → 2NO .
NO is released into air of atmosphere where it forms N02 in presence of lightning discharge.
2NO + 02 → 2NO2
N02 when comes in contact with water vapours to form nitric acid and falls in the form of acid rain
2N02 + H20 →HNO3 + HNO2
2H20 + 4NO2 + 02 → 4HNO3

Question 10.

Explain the basic function of a catalytic converter in an internal combustion engine.
The basic function of a catalytic converter is ‘to eliminate pollutants from exhaust gases before they are discharged into the atmosphere’.

Question 11.

State why acid rain causes ‘nutrient leaching’ when it falls on the earth.
Acid rain causes ‘nutrient leaching’. H+ – Hydrogen ions produced by the decomposition of acid are added to the soil and interact with the metal. The metal Ca, K etc. are displaced from the earth called nutrient leaching.

Question 12.

Give reasons why acid rain affects marine organisms.
Affects marine organisms: Acid rain leach toxic metals like mercury, lead, zinc present in the soil thus toxicty enters rivers and streams and destroys marine organisms.

Question 13.

State the impact of acid rain on the environment, other than soil chemistry and water bodies.
Acid rain changes the pH of the environment: Certain species (aquatic animals) are eliminated at pH less than 6 [Salmons die at pH less than 5.3]

Question 14.

Enumerate the ways by which acid rain can be controlled to prevent its adverse effects on the environment.
Ways to control acid rain:

  1. Using catalytic convertors, which can reduce NO emission from automobiles so that NO, and nitric acid is not formed.
  2. Using C.N.G., Hydro power or wind energy which is cleaner energy and cause less pollution.

Question 15.

State what are ‘green house gases’ and name the major green house gases.
Green house gases: “Are those gases that contribute effectively in retaining heat in the atmosphere.”

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