Hyperconjugation is most useful for stabilising which of the foll

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 Multiple Choice QuestionsMultiple Choice Questions

251.

The IUPAC name of the compound CH subscript 3 CH space equals space CHC space identical to space CH is

  • pent - 4 yn - 2- ene

  • pent - 3-en - 1-yne

  • pent - 2- en-4 -yne

  • pent - 2- en-4 -yne

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252.

Which of the following hydrocarbons is the most reactive towards addition of H2SO4?

  • Ethene

  • Propylene

  • 3-methyl but-1-ene

  • 1-butene


253.

In the reaction,

How many electron donating groups are attached with the carbon atom of unsaturated part of the product 'B' ?

  • Two

  • Three

  • Four

  • None of these


254.

Find out the correct stereoisomeric product for the following reaction,

  • d-form

  • l- from

  • meso-form

  • racemic mixture


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255.

The above reaction is known as

  • aromatisation

  • pyrolysis

  • isomerisation

  • oxidation


256.

Propyne on passing through red hot copper tube forms

  • benzene

  • toluene

  • mesitylene

  • None of these


257.

On warming with silver powder, chloroform is converted into

  • acetylene

  • hexachloroethane

  • 1, 1, 2, 2-tetrachloroethane

  • ethylene


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258.

Hyperconjugation is most useful for stabilising which of the following carbocations?

  • Neo-pentyl

  • Tert-butyl

  • Iso-propyl

  • Ethyl


B.

Tert-butyl

On the basis of hyperconjugation, stability order of different alkyl carbocations is

3° > 2° > 1 ° > methyl

In t-butyl cation, the C-atom bearing the positive charge is attached to three methyl groups, thus it will have maximum hyperconjugate structures, which give it maximum stability.


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259.

Dihedral angle between two methyl groups of n-butane in the gauche and anti forms are

  • 60°, 0°

  • 0°, 60°

  • 60°, 180°

  • 180°, 60°


260.

The homologue of ethyne is

  • C2H2

  • C2H6

  • C3H8

  • C3H4


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