Haloalkanes And Haloarenes(12th Grade > Chemistry ) Questions and answers for exam Preparation

12th Grade > Chemistry

HALOALKANES AND HALOARENES MCQs

Total Questions : 30 | Page 2 of 3 pages

Question 11. Chlorobenzene is

Less reactive than benzyl chloride
More reactive than ethyl bromide
Nearly as reactive as methyl chloride
More reactive than isopropyl chloride

Discuss Question

Answer: Option A. -> Less reactive than benzyl chloride
:
A

Question 12. The correct order of decreasing dipole moment is:

CH3Cl, CH3Br, CH3F
CH3Cl, CH3F, CH3Br
CH3Br, CH3Cl, CH3F
CH3Br, CH3F, CH3Cl

Discuss Question

Answer: Option B. -> CH3Cl, CH3F, CH3Br
:
B
Dipole moment decreases with decrease in electronegativity of halogen. Fluorides have lower dipole moment than chlorides because of smaller C-F bond length which outweights the effect of greater electronegativity

Question 13. The product in the following reaction is

Discuss Question

Answer: Option B. -> CH3Cl, CH3F, CH3Br
:
A

Question 14. The chlorobenzene is generally obtained from a corresponding diazonium salt by reacting it with
[MP PMT 2000]

Discuss Question

Answer: Option B. -> CH3Cl, CH3F, CH3Br
:
A

The Chlorobenzene Is Generally Obtained From A Corresponding...

Question 15. Which of the following sequence of reactions will give 1-bromo 4-trichloro methyl benzene

Toluene Br2−−→Fe o-bromotoluene hν or heat−−−−−−→Cl2
Toluene Br2−−→Fe p-bromotoluene hν or heat−−−−−−→Cl2
Toluene Cl2−−−−−→hν or heat trichloromethyl benzene Fe−→Br2
None of these

Discuss Question

Answer: Option B. -> Toluene Br2−−→Fe p-bromotoluene hν or heat−−−−−−→Cl2
:
B

Which Of The Following Sequence Of Reactions Will Give 1-bro...

Question 16.

H_{3} C - C H_{2} - C | C H_{3} = C H_{2} + H B r \to A

A (predominantly) is

CH3CH2−C|CH3H−CH2Br
CH3−CH−C|CH3H−CH3|Br
CH3−CH−C|CH3H−CH2−CH2Br
CH3−Br|C|CH3−CH2CH3

Discuss Question

Answer: Option D. -> CH3−Br|C|CH3−CH2CH3
:
D

H3C−CH2−C|CH3=CH2+HBr→AA (predominantly) Is

The reaction proceeds via the formation of the more stable carbocation.
Hence, the major product!

Question 17. The compound that will react most readily with NaOH to form methanol is

(CH3)4N⊕I⊝
CH3OCH3
(CH3)3S⊕I⊝
(CH3)3CCl

Discuss Question

Answer: Option A. -> (CH3)4N⊕I⊝
:
A
Electro negativity of N>S
Positive charge on N will make Methyl group more electron deficient than positive charge on 'S'. Therefore (a) will undergoSN²reaction more rapidly than (c)

Question 18. (CH₃)₃CMgCl on reaction with D₂O produces :

(CH3)3CD
(CH3)3OD
(CD3)3CD
(CD3)3OD

Discuss Question

Answer: Option A. -> (CH3)3CD
:
A
(CH₃)₃C - MgCl + D₂O → (CH₃)₃C - D + Mg(OD)Cl

Question 19. The thionyl chloride method is preferred over hydrogen chloride or phosphorous chloride method for the preparation of haloalkanes because both the by-products (SO₂ and HCl) in this case are gases and escape leaving behind pure chloroalkane. This reaction takes place in the presence of

Conc. sulphuric acid
Phosphoric acid
Anhydrous zinc chloride
Pyridine

Discuss Question

Answer: Option D. -> Pyridine
:
D
Pyridine molecule act as a catalyst which is used to neutralise HCl formed.Pyridine also acts as a nucleophile because in the reaction proton is added to alcoholic O due to strong electronegative
SOCl₂ group and proton is removed by pyridine and reforms S=O and Cl^- is removed from SOCl_2.This Cl^- ion reacts with electrophilic C atom of alcohol and displaces SO₂ and another releases another Cl^-
Ion which makes alkyl chloride.

Question 20.