Subject

Chemistry

Class

JEE Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

11.

Identify a species which is not a Bronsted acid but a Lewis acid

  • BF3

  • H3+O

  • NH3

  • HCl


12.

d2sp3 hybridisation of the atomic orbitals gives

  • square planar structure

  • triangular structure

  • tetrahedral structure

  • octahedral structure


13.

The pH of 10-8 M HCl solution is

  • 8

  • 6.9586

  • more than 8

  • slightly more than 7


14.

A group of atoms can function as a ligand only when

  • It is a small molecule

  • It has an unshared electron pair

  • Its a negatively charged ion

  • It is a positively charge ion


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15.

Which of the following is diamagnetic?

  • H2+

  • He2+

  • O2

  • N2


16.

The number of anti-boinding electron present in O2+ molecular ion is

  • 8

  • 6

  • 5

  • 4


17.

The process is spontaneous at the given temperature, if

  • ΔH is +ve and ΔS is -ve

  • ΔH is -ve and ΔS is +ve

  • ΔH is +ve and ΔS is +ve

  • ΔH is +ve and ΔS is equal to zero.


18.

Mesomeric effect involves

  • delocalisation of π- electron

  • delocalisation of σ- electron

  • partial displacement of electrons

  • delocalisation of π and σ- electron


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19.

Alkali metals have negative reduction potential and hence they behave as

  • oxidising agents

  • Lewis bases

  • reducing agents

  • electrolytes


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20.

Cycloalkane formed when 1,4-dibromopentaneis heated with sodium is

  • methyl cyclobutane

  • cyclopentane

  • cyclobutane

  • methyl cyclopentane


A.

methyl cyclobutane

When α,ω-dihalogen derivatives of the alkanes (say 1,4-dbromopentane) are treated with sodium or zinc, the corresponding cycloalkane is formed. The reaction undergoes free radical mechanism.

         

On the other hand α,ω-dihalogen derivatives of the alkanesn which the two halogen atoms are further apart than the 1,6-positions, do not form ring compounds but undergo the Wurtz reaction.


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