CBSE Class 12 Chemistry Haloalkanes And Haloarenes VBQs

MULTIPLE CHOICE QUESTIONS

Question. Arrange the following compounds in increasing order of rate of reaction towards nucleophilic substitution:

(a) a < b < c
(b) a < b < a
(c) a < c < b
(d) c < a < b

Answer: C

Question. Which of the carbon atom present in the molecule given below are asymmetric.

(a) 1, 2 , 3, 4
(b) 2, 3
(c) 1, 4
(d) 1, 2, 3

Answer: B

Question. Which of the following compound will undergo recevisation when solution of KOH hydrolyses?

(a) i and iv
(b) ii and iv
(c) iii and iv
(d) iv

Answer: D

Question. Which of the following state are correct
(a) Benzyl halides are more reactive than vinyl and anyl halides
(b) Vinyl/halides are more reactive than alkyl halides
(c) Aryl halides are less reactive than alkylhalide
(d) Aryl halides are more reactive than benzyl halides

Answer: A,C

Question. In a S_Nl reaction on chiral centres, there is
(a) 100 % retention
(b) 100 % inversion
(c) 100 % recenisation
(d) inversion is more than retention leading to recenisation

Answer: D

Question. The order of reactivity of following alcohols with halogen acid (HX) is

(a) i > ii > iii
(b) iii > ii > i
(c) ii > i > iii
(d) i > iii > ii

Answer: B

Question. The reaction of C₆H₅—CH==CH—CH₃ with HBr produces

Answer: C

Question. The increasing order of reactivity of the following halides for the S_Nl reaction is

(a) iii < ii < i
(b) ii < i < iii
(c) i < iii < ii
(d) ii < iii < i

Answer: B

Question. Arrange the following compound in increasing order of rate of reaction towards nucleophilic substitution.

(a) i < ii < iii
(b) i < iii < ii
(c) ii < i < iii
(d) iii < ii < i

Answer: A

Question. Arrange the following compounds in increasing order of their boiling point
(i) (CH₃)₂CH₂CH₂—Br
(ii) CH₃—(CH₂)₃ —Br
(iii) (CH₃)₃C—Br
(a) ii < i < iii
(b) i < ii < iii
(c) iii < i < ii
(d) iii < ii < i

Answer: C

Question. In S_N2 reactions, the correct order of reactivity fo the following compounds:
(i) CH₃Cl
(ii) (CH₃)₃CCl
(iii) (CH₃)₂CHCl
(iv) CH₃CH₂—Cl
(a) i > ii > iii > iv
(b) iv > iii > ii > i
(c) i > iv > iii > ii
(d) iv > i > ii > iii

Answer: C

Question. Toluene reacts with halogen in thepresence of FeCl₃ giving ortho and parabola compound. The reactions is
(a) electrophilic elimination reaction
(b) electrophilic substitution
(c) free radical addition reaction
(d) nucleophilic substitution

Answer: B

Question. In the reaction

Answer: A

Question. Chlorobenzene is formed by reactionj of chlorine with benzene in presence of AlCl₃. Which of the following species attacks the beneze ring in this reaction.
(a) Cl^–
(b) Cl⁺
(c) AlCl₃
(d) AlCl₄^–

Answer: B

Question.

Answer: A

Question. The reaction of toluene with Cl₂ in the presence of FeCl₃ gives ‘X’ and the reaction with Cl₂ in presence of light gives ‘Y’. Thus ‘X’ and ‘Y’ are:
(a) ‘X’ = benzyl chloride and ‘Y’ = m-chlorotoluene
(b) ‘X’ = benzyl chloride and ‘Y’ = o-chlorotoluene
(c) ‘X’ = m-chlorotoluene and ‘Y’ = p-cholorotoluene
(d) ‘X’ = p-chlorotoluene and ‘Y’ = benzyl chloride.

Answer: D

Question. Anyl halides are less reactive toward nucleophilic substitution reaction than alkyl halides due to
(a) the formation of stable carbonimion
(b) resonance stabilization
(c) longer carbon-halogen bond
(d) sp² hybridised carbon attached to halogen

Answer: B,D

Question. A new carbon carbon bond is possible in the following reaction reactions:

Answer: A,D

Question. Which of the following contain sp² hybridised carbon bonded to X?

Answer: B,D

Question. The IUPAC name of the following compound are

(a) 1-chloro-4-methyl benzene
(b) 4-chlorotoluene
(c) 1-methyl-4-chlorobenzene
(d) 4-methylchlorobenzene

Answer: A,B

Note : In the following questions a statement of assertion followed by a statement of reason is given. Choose the correct Answer. out of the following choice.
(a) Both assertion and reason are Correct, and reason is the correct explanation of the assertion.
(b) Both assertion and reason are True, but reason is not the correct explanation of the assertion.
(c) Assertion is Incorrect, but reason is Correct.
(d) Both assertion and reason are Incorrect.

Assertion and Reasoning

Question. Assertion : S_N2 reaction proceeds with inversion of configuration. 
Reason : S_N2 reactionoccurs in one step

Answer: B

Question. Assertion : Treatment of chloroethane with saturated solution of AgCN give ethyl isocyanide as major product.
Reason : Cyanide ion (CN^–) is an ambident nucleophile.

Answer: B

Matching Column Type

Question. Match the items of column 1 and column 2
Column1                                         Column 2
(A) CH₂Cl₂                                          P. Antiseptic
(B) CCl₄                                              Q. Insecticide
(C) (p-Cl C₆H₄)CHCCl₃                  R. Pyrene
(D) CHI₃                                      S. Refrigerend
(a) A–R, B–Q, C–S, D–P
(b) A–S, B–R, C–Q, D–P
(c) A–Q, B–P, C–S, D–R
(d) A–P, B–S, C–R, D–Q

Answer: B

Question. Match the items of column 1 and column 2

(a) A–P, B–Q, C–S, D–P
(b) A–S, B–R, C–Q, D–P
(c) A–Q, B–P, C–S, D–R
(d) A–P, B–S, C–R, D–Q

Answer: B

VERY SHORT ANSWER TYPE QUESTIONS 

Question. Give IUPAC name of :

Answer:

1-chloro-2, 3-dibromo-2-methyl pentane

Question. Identify A and B in each of the following processes :

Answer:

A : CH₃ – CH₂ – CN; B : CH₃CH₂CH₂NH₂

Question. Draw the structure of 4-bromo-3-methylpent-2-ene.

Answer:

Question. An alkyl halide having molecular formula C₄H₉Cl is optically active. What is its structure ?

Answer:

Question. An organic compound ‘A’ on treatment with KCN gave B which on hydrolysis with dil. HCl gave acetic acid. Identify A.

Answer:

A : CH₃Cl

Question. Write IUPAC name of iodoform.

Answer:

Triiodomethane

Question. Write the IUPAC name of the following compound :

Answer:

3-bromo-2-methylprop-1-ene

Question. Arrange the following in order of their increasing reactivity in nucleophilic substitution reactions : CH₃F, CH₃I, CH₃Br, CH₃Cl
Answer:

CH₃F < CH₃Cl < CH₃Br < CH₃I

Question. Complete the reaction :

Answer: 

Question. Give one chemical test to distinguish between chlorobenzene and benzyl chloride ?
Answer:

AgNO₃ test

Question. Why iodoform show antiseptic properties ?
Answer:

Due to free liberated iodine.

SHORT ANSWER TYPE QUESTIONS

Question. Give reasons :

(i) Boiling point of alkyl bromide is higher than alkyl chloride.

(ii) Alkyl halides are better solvents than aryl halides.
Answer:

(i) High magnitude of van der Waal’s forces in alkyl bromides.

(ii) C – X is more polar in haloalkanes.

Question. Name the reagents used to convert :

(i) 2-chloropropane to 2-nitropropane

(ii) Chloroethane to n-butane

Answer: 

(i) AgNO₂

(ii) Na/dry ether

Question. Draw structure of monohalo product in each of the following :

Answer:

Question. Ravi is a student of class VI fell down and got hurt Sam is a boy class XII immediately took him to the doctor and the doctor dressed the wound with the halogen compound.

(i) What is the name and formula of the compounds?

(ii) Write any one method of preparation.

(iii) What values can you find in Ravi?

Answer:

i. iodoform,CHI₃

ii. CH₃CH₂OH+NaOI→CHI₃+HCOOH

iii. Ravi is alert ,helping and kind in nature.

Question. We all know that Freon 12 is used as refrigerant and it caused ozone layer depletion.

(i) What are the other gases cause ozone layer depletion?

(ii) How can you save your environment?

(iii) Give one more use of freons.

Answer:

i. CO₂

ii. by using public vehicle, and filtering fumes from factories

iii. used as propellant

Question. Sam find a man putting his handkerchief on the face of a lady and she fainted. Sam immediately called for help and the other man ran away and took her to the hospital.

(i) What values can you find in Sam?

(ii) Can you give one use of chloroform?

(iii) Chloroform should be filled bottle up to the brim in brown bottle. Why?

Answer:

i. Sam is alert ,helping and has general awareness.

ii. used as anaesthetic.

iii. Chloroform will react with oxygen and form poisonous gas phosgene. 

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