CBSE Questions for Class 11 Medical Chemistry Environmental Chemistry Quiz 9 - MCQExams.com

Pollution can be controlled by :
  • Sewage treatment
  • Checking atomic blasts
  • Manufacturing electrically operated vehicles
  • All the above
Phenomenon of 'industrial melanism' demonstrates:
  • Geographical isolation
  • Reproduction isolation
  • Natural selection
  • Induced mutation
Long term usage of insecticides results in
  • Sensitivity in insects
  • Kills insects
  • Resistance in insect
  • Decrease in insect population
Which harmful radiations are absorbed by ozen layer?
  • UV
  • X-RAY
  • Visible light
  • Gamma rays
What will happen if chemical fertilizers are used for a longer time.
  • soil always stays fertile for plant growth
  • soil fertility is damaged
  • soil stops responding to fertilizers
  • soil health is maintained
Identify the incorrect statement from the following
  • Oxides of nitrogen in the atmosphere can cause the depletion of ozone layer
  • Ozone absorbs the intense ultraviolet radiations of the sun
  • Depletion of ozone layer is because of its chemical reactions with  CFC
  • Ozone absorbs infrared radiations
In the upper layers of atmosphere, ozone is formed ?
  • By action of electric discharge on oxygen molecules
  • By action of ultraviolet rays on oxygen molecules
  • By action of infrared rays on oxygen molecules
  • Due to sudden drop of pressure
Why ozone is known as 'chemical weed ' ?
  • Because it is formed by chemical reactions
  • Because it is harmful as well useful
  • Because it is harmful, just like weeds for mankind
  • Ozone is not designated as chemical weed
Water filled in two glasses $$A$$ and $$B$$ have $$BOD$$ values of $$10$$ and $$20$$, respectively. The correct
statement regarding them, is:
  • $$A$$ is more polluted than $$B$$
  • $$A$$ is suitable for drinking, whereas $$B$$ is not
  • $$B$$ is more polluted than $$A$$
  • Both $$A$$ and $$B$$ are suitable for drinking
Ozone hole over Antarctica appear during
  • Spring
  • Autumn
  • Summer
  • Winter
500 ml of a sample COD of water required 19.6 mg of $$ K_2Cr_2O_7 $$ of water sample is?
  • 9 PPM
  • 8PPM
  • 16.8 PPM
  • 10 PPM
Biochemical Oxygen Demand (BOD) value can be a measure of water pollution caused by the organic matter. Which of the following statement is correct ?
  • Aerobic bacteria decrease the BOD value.
  • Anaerobic bacteria increase the BOD value.
  • Clean water has BOD value higher than 10 ppm.
  • polluted water has BOD value higher
Water samples with $$BOD$$ values of $$4 ppm$$ and $$18 ppm$$, respectively, are:
  • highly polluted and clean
  • highly polluted and highly polluted
  • clean and highly polluted
  • clean and clean
The atmosphere between  the heights $$10$$ to $$50$$ kilometer above the sea level is :
  • troposphere
  • stratosphere
  • mesosphere
  • ionosphere
The concentration of dissolved oxygen (DO) in cold water can go upto :
  • 10 ppm
  • 14 ppm
  • 16 ppm
  • 8 ppm
All except which cause pollution:
  • thermal power plant
  • hydro - electric plant
  • nuclear power plant
  • automobiles
Which of these gases is an atmospheric pollutant?
1 carbon monoxide
2 nitrogen dioxide
3 sulfur dioxide.
  • $$1$$ only
  • $$2$$ only
  • $$3$$ only
  • $$1, 2$$ and $$3$$
Which of the following practices will not come under green chemistry?
  • If possible making use of soap made of vegetable oils instead of using synthetic detergents
  • Using $$H_{2} O_{2}$$ for bleaching purpose instead of using chlorine based bleaching agents
  • using bicycle for travelling small distance instead of using petrol / diesel based vehicles
  • Using plastic cans for neatly storing substance
Which of the following conditions shows the polluted environment ?
  • pH of rain water is $$ 5 . 6 $$
  • amount of carbondioxide in the atmosphere is $$ 0.03 % $$
  • biochemical oxygen demand 10 ppm .
  • eutrophicition
Chlorine atoms in the upper atmosphere cause the breakdown of ozone.
$$Cl+O_3\rightarrow O_2+ClO$$
$$ClO+O\rightarrow Cl+O_2$$
Which statements about these chlorine atoms are correct?
$$1$$. The chlorine atoms act as catalysts.
$$2$$. The chlorine atoms are free radicals.
$$3$$. The chlorine atoms are formed by heterolytic fission of a covalent bond in chlorofluorocarbons.
  • $$1, 2$$ and $$3$$ are correct
  • $$1$$ and $$2$$ only are correct
  • $$2$$ and $$3$$ only are correct
  • $$1$$ only is correct
Chlorine atoms in the upper atmosphere cause the breakdown of ozone.
$$Cl+O_3\rightarrow O_2+ClO$$
$$ClO+O\rightarrow Cl+O_2$$
Which statements are correct when referring to these chlorine atoms?
$$1$$. The chlorine atoms act as catalysts.
$$2$$. The chlorine atoms are free radicals.
$$3$$. The chlorine atoms are formed by heterolytic fission of a covalent bond in chlorofluorocarbons.
  • $$1, 2$$ and $$3$$ are correct
  • $$1$$ and $$2$$ only are correct
  • $$2$$ and $$3$$ only are correct
  • $$1$$ only is correct
Antiknocking agent used for unleaded gasoline is:
  • $$BXT$$
  • $$TBA$$
  • $$MTBE$$
  • all of these
Which one is not the correct statement?

Pollution means:
  • the presence of anything in the environment in excess of required limit
  • anything put into the environment which was not there in its natural state.
  • direct or indirect changes in one or more components of the ecosystem which are not harmful to living organisms
  • international release of any chemical substance in the environment with harmful effects
Carbon monoxide, $$CO$$, nitrogen dioxide, $$NO_{2}$$, and sulfur dioxide, $$SO_{2}$$, are all atmospheric
pollutants.
Which reaction concerning these compounds occurs in the atmosphere?
  • $$CO$$ is spontaneously oxidised to $$CO_{2}$$
  • $$NO_{2}$$ is reduced to $$NO$$ by $$CO$$
  • $$NO_{2}$$ is reduced to $$NO$$ by $$SO_{2}$$
  • $$SO_{2}$$ is oxidised to $$SO_{3}$$ by $$CO_{2}$$
Which pair of compounds would make an NPK fertiliser?
  • Ammonium sulfate and potassium phosphate
  • Calcium hydroxide and ammonium nitrate
  • Calcium phosphate and potassium chloride
  • Palcium phosphate and potassium chloride
The knocking will be maximum when the mixture of the fuel is
  • straight-chain
  • iso-chain
  • neo-chain
  • none of these
Which of the following substance is used as an anti nock compound?
  • TEL
  • Lead tetrachloride
  • Lead acetate
  • $$\mathrm{ C_{2}H_{5}PbCl} $$
If BOD of river is high, it means that the river is:
  • not polluted
  • very much polluted with inorganic chemicals
  • very much polluted with organic chemicals which are decomposed by micro- organisms
  • polluted with pesticides
Pollution can be controlled if :
  • all automobiles must be fitted with exhaust system's catalytic converters
  • use of fossil fuels must be minimised and non-conventional energy sources should be developed
  • emphasis on green chemistry is given
  • population is stabilised
When huge amount of sewage is dumped in a river, the BOD will:
  • increase
  • remain unchanged
  • decrease
  • increase or decrease
The following reactions occur in the stratosphere:
  • $$O_2 +UV \to O+O$$
  • $$O_2 +O \to O_3$$
  • $$Cl +O_3 \to ClO+O_2$$
  • $$SO_3 +H_2O \to H_2SO_4$$
Pollutant is a chemical substance or factor which disturbs:
  • our balanced environment
  • geochemical cycles
  • flora of any region
  • fauna of any region
Most important cause of soil pollution is :
  • iron junks
  • glass junks
  • detergents
  • plastics
Which one is not a correct statement? To minimise pollution:
  • manures and biofertilizers should be used in place of chemical fertilizers
  • all nuclear tests must be stopped
  • green belts in cities should be developed
  • domestic garbage must be burnt
Which statement is not correct?
  • $$CO$$ is the main air pollutant
  • All pollutants are not wastes
  • Water is polluted by dissolved oxygen
  • Lichens are pollution indicators
An object is located at a height of $$5\ km$$ from the surface of the earth. The object is located in which part of the atmosphere?
  • Thermosphere
  • Mesosphere
  • Stratosphere
  • Troposphere
The term "water pollution" can be defined in several ways. Which of the following statements does not give the correct definition?
  • The addition of undesirable substances to water bodies
  • The removal of desirable substances from water bodies
  • A change in pressure of the water bodies
  • A change in temperature of the water bodies
Biochemical oxygen demand , (BoD) is a measure of organic material present in water . BoD value less than 5 ppm indicates a water sample to  be ...
  • rich in dissolved oxygen
  • poor in dissolved oxygen
  • highly polluted
  • not suitable for aquatic life
The ozone layer forms natural by ;
  • the interactions of CFC with oxygen
  • the interaction of UV radiation with oxygen
  • the interaction of IR radiation with oxygen
  • the interaction of oxygen and water vapour
Planting more and more trees helps to :
  • reduce $$ CO_{2}$$ in the air
  • increase $$ CO_{2}$$ in the air
  • reduce $$ O_{2}$$ in the air
  • reduce $$ CO_{2}$$ and increase $$ O_{2}$$ in the air
The gaseous envelope around the earth is known as atmosphere . The lowest layer of  this is extended upto 10 km from sea level, this layer is ...
  • Stratosphere
  • Troposphere
  • Mesosphere
  • Hydrosphere
Say true or false:
Chlorofluorocarbons deplete the ozone layer in the atmosphere.
  • True
  • False
Which of the following statements is correct?
  • Ozone hole is a hole formed in stratosphere from which ozone out.
  • Ozone hole is a hole formed in the troposphere from which ozone oozes out
  • Ozone is hole is tinning of zone layer of stratosphere at some places
  • Ozone hole means vanishing of zone layer around the earth completely
Which of the following are the main sources of water pollution?
  • Sewage and domestic wastes
  • Household detergents that are used for washing purposes
  • Oil spills 
  • All of these
________ poisons sea life.
  • Industrial waste
  • Household detergents
  • Oil spills
  • Heavy metals

Assertion :Biocides are effective against animals.

Reason :Algicides are effective against weeds.
  • If both the assertion and the reason are true and the reason is a correct explanation of the assertion
  • If both the assertion and reason are true but the reason is not a correct explanation of the assertion
  • If the assertion is true but the reason is false
  • If both the assertion and reason are false
  • If the assertion is false but reason is true
The most likely reason for the development of resistance to pesticides in insects, damaging a crop, is
  • Direct mutation
  • Acquired heritable changes
  • Random mutation
  • Genetic recombination
Cochineal insects have proved very useful for the control of
  • Eicchornia
  • Cactus
  • Weeds
  • Parathenium
Regular use of which of the following fertilizers increases the acidity of soil ?
  • Potassium nitrate
  • Urea
  • Superphosphate of lime
  • Ammonium sulphate
Ozonosphere occurs at height of
  • 8-10 km. above poles
  • 8-10 km. above equator
  • 11-16 km above poles
  • 11-16 km above equator
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Practice Class 11 Medical Chemistry Quiz Questions and Answers