CBSE 11TH CHEMISTRY (Test 6)



Tag: cbse 11th chemistry
Q.1
Stratosphere is a region of the atmosphere which contains :
A. Water vapour and clouds
B. Plants
C. Ozone layer
D. Air
Answer : Option C
Explaination / Solution:

Stratosphere, which is the second layer of atmosphere, contains ozone layer that absorbs UV-radiation from sun's rays.

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Q.2
In cold places, vegetables, fruits and flowers are grown in glass covered areas called green houses. This is because of one or more of the following. Choose the most appropriate :
A. It traps the solar energy
B. It absorbs the infrared radiation
C. It maintains the temperature
D. It maintains the temperature as well as traps the solar energy
Answer : Option D
Explaination / Solution:

In cold places, vegetables, fruits and flowers are grown in glass covered areas as they maintains the temperature as well as traps the solar energy. Glass is opaque to IR (heat) radiation and it partly absorbs and partly reflects the heat which maintains the temperature and traps the solar energy.

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Q.3
Metathesis is developed by :
A. Chauvin, Watson and Schrock
B. Gruubs, Watson and Crick
C. Chauvin, Gruubs and Schrock
D. Chauvin, Crick and Schrock
Answer : Option C
Explaination / Solution:

Yves Chauvin, Robert H. Grubbs and Richard R Schrock won the noble prize in 2005 for designing the method of metathesis.

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Q.4
Unleaded paint and petrol were introduced because:
A. European Parliament told us to
B. Lead was proven to affect the brain and cause mental impairment
C. Unleaded petrol made cars go faster
D. It was cheaper to produce than leaded products
Answer : Option B
Explaination / Solution:

Unleaded paint and petrol were introduced because lead affect the brain and cause mental impairment

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Q.5
The ozone layer found high in the stratosphere:
A. Is toxic to plants
B. Protects against the suns harmful UV rays
C. Is capable of disintegrating fabric and rubber
D. Can react with atmospheric pollutants to form smog
Answer : Option B
Explaination / Solution:

The ozone layer found high in the stratosphere Protects against the suns harmful UV rays

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Q.6
n the Wurtz reaction method of preparation of alkanes, the stoichiometric coefficient of Sodium is
A. 2
B. 5
C. 3
D. 1
Answer : Option A
Explaination / Solution:

Wurtz reaction is used for the preparation of alkanes from alkyl halides in the presence of sodium and dry ether.For example: CH3Br + 2Na +BrCH3 ---------> CH3CH3 + 2NaBr

Thus two atoms of Na are used.


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Q.7
The reaction given below is used to produce polythene. This is an example of _______ reaction

A. Rearrangement reaction
B. Substitution reaction
C. Polymerization reaction
D. Addition reaction
Answer : Option C
Explaination / Solution:

In polymerisation reaction many monomeric units combine to form a big macromolecule.

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Q.8
Some of the polynuclear hydrocarbons having fused benzene ring system have the property of being
A. malleable
B. nonflammable
C. conductive
D. carcinogenic
Answer : Option D
Explaination / Solution:

Polynuclear hydrocarbons are carcinogenic,i.e. cancer producing

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Q.9
Which branched chain isomer of the hydrocarbon with molecular mass 72u gives only one isomer of mono substituted alkyl halide?
A. Isohexane
B. Neohexane
C. Tertiary butyl chloride
D. Neopentane
Answer : Option D
Explaination / Solution:

(CH3)3CCH3 + HX(X=Cl,Br,I) ------------> (CH3)3CCH2X  

Hence a monosubstituted derivative is formed.


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Q.10

In the following sequence of reactions, the alkene is converted to  compound   


The compound  is --------- ?

A. CH3 CHO
B. CH3CH2COCH3
C. CH3COCH3
D. CH3CH2CHO
Answer : Option A
Explaination / Solution:

The given sequence of conversion  steps  represent Ozonolysis of 2-Butene , which follows the following path ,

1 .   Formation of an unstable intermediate / ozonide

2 . Cleavage   of the  intermediate / ozonide  by  to smaller molecules , giving out the compound   , which is  CH3 CHO  (  Ethanal )  

 

The reaction is well depicted as below ,  

,


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