Wednesday, August 18, 2021

Organic Chemistry- Some Basic Principle and Techniques : Chemistry

 

Q.1. The number of tertiary C-atoms in 2,2,4,4-tetra methyl pentane is

A) 1

B) 2

C) 3

D) 4

Explanation-

There are two carbon atoms, i.e., C-2 and C-4 which are tertiary in nature.


Q.2.  Chlorine in vinyl chloride is less reactive because 

A) spblank squared - Hybridized carbon has more acidic character than spblank cubed - hybridized carbon 

B) C - Cl Bond develops partial double bond character 

C) Of resonance

D) Both (b) and (c) 

Explanation-

In vinyl chloride, because of resonance C-Cl bond acquires some double bond character which makes it less reactive.


Q.3.  Which group has the maximum inductive effect ?

A) -NOblank subscript 2

B) -CN

C) -COOH

D) -F

Explanation-

The correct order of I-effect exerted by the given groups is negative NO subscript 2 greater than negative CN greater than negative negative COOH greater than negative straight F.


Q.4.  Homolytic fission of C - C bond in ethane gives an intermediate in which carbon is ….hybridized.

A) spblank cubed -Hybridized 

B) spblank squared-Hybridized 

C) sp- Hybridized 

D) spblank squared d-Hybridized

Explanation-

Homolytic fission results in free radical and in free radical the carbon carrying odd electrons is spblank squared-Hybridized. 

Q.5.  Ease of abstraction of hydrogen is greater when attached to 

A) 1degree Carbon 

B) 2degree Carbon 

C) 3degree Carbon 

D) Neo-Carbon 

Explanation- 

Order of ease of abstraction of hydrogen  is 3 degree space greater than space 2 degree space greater than 1 degree. 


Q.6.  Which pair represents chain isomers ?

A) CH subscript 3 CHCI subscript 2 space and space CICH subscript 2 CH subscript 2 CI

B) Prophyll alcohol and isopropyl alcohol

C) 2-Methylbutane and neo - pentane 

D) Diethyl ether and propyl ether 

Explanation-

CH subscript 3 minus CH with vertical line with CH subscript 3 on top on top minus CH subscript 2 minus CH subscript 3 space space space space space space space space space space space space space table row blank blank cell CH subscript 3 end cell blank blank row blank blank vertical line blank blank row cell CH subscript 3 end cell long dash straight C long dash cell CH subscript 3 end cell row blank blank vertical line blank blank row blank blank cell CH subscript 3 end cell blank blank end table left parenthesis Methylbutane space left parenthesis straight C subscript 5 straight H subscript 12 right parenthesis space space space space space space space space space space space space space space space space space space space space space space space Neopentane space left parenthesis straight C subscript 5 straight H subscript 12 right parenthesis

They are chain isomers.


Q.7.  An alkane formal isomers if the number of carbon atoms is 

A) greater or equal than 1 

B) greater or equal than 2

C) greater or equal than 3

D) greater or equal than 4

Explanation-

At least four carbon atoms  must be there in an alkane to show isomerism .

CH subscript 3 minus CH subscript 2 minus CH subscript 2 minus CH subscript 3 space space space space space space space space space table row blank cell CH subscript 3 end cell blank row blank vertical line blank row cell CH subscript 3 end cell cell negative straight C end cell cell negative OH end cell end table straight n minus butyl space alcohol space space space space space space space space space space space space space space space space space space space space space space space space space space space Isobutane 


Q.8.   Aldehydes are isomeric with ….of same molecular formula 

A) Alcohols 

B) Ketones 

C) Ethers 

D) Esters 

Explanation-

Aldehydes are isomeric with ketones. For example,space straight C subscript 3 straight H subscript 6 straight O exists as

stack CH subscript 3 CH subscript 2 CHO space and space with left parenthesis Aldehyde right parenthesis below table row blank cell stack vertical line vertical line with straight O on top end cell blank blank row cell CH subscript 3 end cell cell negative straight C end cell cell negative CH subscript 3 end cell blank row blank cell left parenthesis Ketone right parenthesis end cell blank blank end table 


Q.9.  Number of possible alkynes with the formula straight C subscript 5 straight H subscript 8 

A) 2

B) 3

C) 4

D) 5

Explanation-

Possible Isomers of straight C subscript 5 straight H subscript 8 are

i) HC identical to straight C minus CH subscript 2 minus CH subscript 2 minus CH subscript 3

ii) HC identical to straight C minus CH with vertical line below minus CH subscript 3 space space space space space space space space space space space space space space space space space CH subscript 3

iii) CH subscript 3 minus straight C identical to straight C minus CH subscript 2 minus CH subscript 3 


Q.10.  The number of isomeric xylenes is 

A) 3

B) 2

C) 4

D) 5



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