CBSE 11TH CHEMISTRY (Test 3)



Tag: cbse 11th chemistry
Q.1
Dichloro-diphenyl-trichloro-ethane (DDT), plastic materials, heavy metals etc. belong to which of the following category of pollutants in environment :
A. Bio-degradable
B. None of the above
C. Slowly degradable
D. Non-biodegradable
Answer : Option D
Explaination / Solution:

DDT, plastic materials and heavy metals like cadmium, mercury and arsenic are not degradable by natural biological processes by bacteria or any other microbe. Therefore they are non-biodegradable.

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Q.2
Carbon monoxide is one of the most dangerous air pollutants and is produced as a result of :
A. Combustion of fuel in automobiles at high temperatures
B. Complete combustion of fuel used in automobiles
C. Complete combustion of fossil fuel
D. Incomplete combustion of carbon, firewood, petrol
Answer : Option D
Explaination / Solution:

Carbon monoxide is produced by incomplete combustion of carbon, firewood, petrol.

The reaction is as follows : 

2C + O2 -----> 2CO


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Q.3
Measure of the amount of organic material in the water, in terms of how much oxygen will be required to break it down biologically is termed as :
A. hydrosphere measure
B. Eutrophication value
C. Biochemical Oxygen Demand (BOD)
D. measure of polluted water
Answer : Option C
Explaination / Solution:

Measure of the amount of organic material in the water, in terms of how much oxygen will be required to break it down biologically is termed as Biochemical Oxygen Demand (BOD)

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Q.4
Acid rain does not cause :
A. Damage to trees
B. Erosion of limestone and marble
C. Lakes with a very low pH
D. Global warming
Answer : Option D
Explaination / Solution:

Acid rain does not cause Global warming as it does not release any greenhouse gas in the atmosphere.

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Q.5
The balance of carbon dioxide and oxygen has been upset by :
A. Increasing human population
B. Burning fossil fuels and deforestation
C. Large scale deforestation
D. Excessive burning of fossil fuels
Answer : Option B
Explaination / Solution:

The balance of carbon dioxide and oxygen has been upset by Burning fossil fuels and deforestation which causes release of excessive CO2 and reduced O2

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Q.6
in cycloalkanes carbon atoms form
A. a zigzag chain
B. a open coiled chain
C. a an open chain
D. a closed chain or a ring
Answer : Option D
Explaination / Solution:

Cycloalkanes contain single bond between the carbon atoms,they form ring structures and have the general formula CnH2n

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Q.7
Stereoisomeric alkenes due to different arrangement of atoms or groups in space are referred to as
A. geometric isomers
B. chain isomers
C. constitutional isomers
D. position isomers
Answer : Option A
Explaination / Solution:

Isomers which have the same structural formulae but difffer in the relative spatial arrangements of atoms or groups around the double bond are called geometric isomers.athus geometrical isomers are atype of stereoisomers.

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Q.8
Aromatic compounds are charachterized by the presence of _____ π electrons in the ring where n is an integer (n = 0, 1, 2, . . .).
A. (4n - 2)
B. (4n + 1)
C. 4n
D. (4n + 2)
Answer : Option D
Explaination / Solution:

Huckel rule which explains the unusual stability of cyclic conjugated polyenes(i.e. aromatic compounds) over other cyclic unsaturatrd compounds which do not contain (4n+2) pi electrons.

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Q.9
Arrange the following carbanions in order of their decreasing stability.(A) H3C – C C (B) H – C ≡ C (C) 
A. C > A > B
B. A > B > C
C. C > B > A
D. B > A > C
Answer : Option D
Explaination / Solution:

In B,the '-' charge is on sp hybridised C atom so the negative charge is stabilised.In A,there is an alkyl group attached to sp hybridised carbon which destabilises the negative charge. In C,the '-' charge is on a sp3 hybridised carbon and is hence the least stable.

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Q.10
Which one of these is NOT TRUE for benzene? Explanation: Benzene forms mono substituted product.
A. Heat of hydrogenation of benzene is less than the theoretical value
B. The bond angle between carbon-carbon bonds is 
C.
There are three carbon-carbon single bonds and three carbon-carbon double bonds

D.
It forms only one type of monosubstituted product

Answer : Option C
Explaination / Solution:
No Explaination.


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