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 Multiple Choice QuestionsMultiple Choice Questions

511.

Find out the correct stereoisomeric product for the following reaction,

  • d-form

  • l- from

  • meso-form

  • racemic mixture


512.

The above reaction is known as

  • aromatisation

  • pyrolysis

  • isomerisation

  • oxidation


513.

Propyne on passing through red hot copper tube forms

  • benzene

  • toluene

  • mesitylene

  • None of these


514.

On warming with silver powder, chloroform is converted into

  • acetylene

  • hexachloroethane

  • 1, 1, 2, 2-tetrachloroethane

  • ethylene


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515.

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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516.

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

  • 60°, 0°

  • 0°, 60°

  • 60°, 180°

  • 180°, 60°


517.

The homologue of ethyne is

  • C2H2

  • C2H6

  • C3H8

  • C3H4


518.

Which one of the following alkenes will react faster with H2 under catalytic hydrogenation conditions?

(R = Alkyl substituent)


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519.

The least energetic conformation of cyclohexane is:

  • Boat form

  • Half chair form

  • Chair form

  • Twisted form


520.

By which one of the following compounds both CH4 and CH3 - CH3 can be prepared in one step?

  • CH3I

  • CH3OH

  • CH3CH2I

  • C2H5OH


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