Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev

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Q.1. The major product of the following reaction is:    (2019)
Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
(1) Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
(2) Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
(3) Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
(4) Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
Ans.
(1)
Mechanism involved for the given reaction is:
Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev

Q.2. Which amongst the following is the strongest acid?    (2019)
(1) CHBr3
(2) CHI3
(3) CH(CN)3
(4) CHCl3
Ans.
(3)
Due to the resonance stabilisation of the conjugate base, CH(CN)3 is the strongest acid amongst the given compounds.
Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
The conjugate bases of CHBr3 and CHl3 are stabilised by inductive effect of halogens. This is why, they are less stable. Also, the conjugate base of CHCl3 involves back-bonding between 2p and 3p orbitals

Q.3. The major product of the following reaction is:    (2019)
Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
(1) Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
(2) Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
(3) Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
(4) Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
Ans.
(1)
Dehydrohalogenation (β-elimination) occurs as:
Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev

Q.4. Which hydrogen in compound (E) is easily replaceable during bromination reaction in presence of light?    (2019)
Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
(1) α - hydrogen
(2) γ - hydrogen
(3) δ - hydrogen
(4) β - hydrogen
Ans.
(2)
Allylic H is replaced due to the greater stability of al-lylic free radical.
Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev

Q.5. The major product of the following reaction is:    (2019)
Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
(1) Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
(2) Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
(3) Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
(4) Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
Ans. 
(2)
Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev

Q.6. The major product of the following reaction is:    (2019)
Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
(1) Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
(2) Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
(3) Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
(4) Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
Ans.
(2)
Heating of the given compound in presence of strong base is favoured for elimination reaction resulting in more stable alkene.
Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev

Q.7. The major product of the following reaction is:    (2019)
Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
(1) Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
(2) Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
(3) Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
(4) Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
Ans.
(1)
Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev

Q.8. The major product of the following reaction is:    (2019)
Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
(1) Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
(2) Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
(3) Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
(4) Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
Ans. 
(3)
Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev

Q.9. The major product of the following reaction is:    (2019)
Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
(1) Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
(2) Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
(3) Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
(4) Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
Ans. 
(3)
Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev

Q.10. Increasing order of reactivity of the following compounds for SN1 substitution is:    (2019)
Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRevPrevious year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
(1) (B) < (C) < (D) < (A)
(2) (B) < (C) < (A) < (D)
(3) (B) < (A) < (D) < (C)
(4) (A) < (B) < (D) < (C)
Ans.
(3)
In SN1 reaction carbocation acts as an intermediate.
Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
Carbocation produced by (C) is more stable than carbocation produced by (D) due to + I effect of -OCH3 group.
Further in (A) there is formation of tertiary carbocation after rearrangement while (B) is primary carbocation.
Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
So, the correct order is (C) > (D) > (A) > (B).

Q.11. Which of the following potential energy (PE) diagrams represents the SN1 reaction?    (2019)
(1) Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
(2) Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
(3) Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
(4) Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
Ans.
(1)
The SN1 reaction energy diagram illustrates the dominant part of the substrate with respect to the reaction rate.
The rate determining step is the formation of the intermediate carbocation.
Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev

Q.12. Increasing rate of SN1 reaction in the following compounds is:    (2019)
Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRevPrevious year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
(1) (A) < (B) < (C) < (4)
(2) (B) < (A) < (C) < (D)
(3) (B) < (A) < (D) < (3) 
(4) (A) < (B) < (D) < (C)
Ans.
(2)
The rate of SN1 is decided by the stability of carbocation formed in the rate determining step.
Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev

Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
Carbocation(D) is most stable due to +R effect of CH3O group, (C) is stabilised by +I and +H effects of the CH3 group; (B) is least stable due to -I effect of MeO group. So increasing order of rate of SN1 is (B) < (A) < (C) < (D)

Q.13. The major product of the following reaction is    (2019)
Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
(1) Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
(2) Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
(3) Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
(4) Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
Ans. 
(3)
Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev

Q.14. The major product ‘Y’ in the following reaction is:    (2019)
Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
(1) Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
(2) Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
(3) Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
(4) Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
Ans.
(3)
Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev

Q.15. Which one of the following is likely to give a precipitate with AgNO3 solution?    (2019)
(1) CH2 = CH —Cl
(2) CCI4
(3) CHCl3
(4) (CH3)3CCl
Ans.
(4)
Carbocation is formed on reaction with Ag+
Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev is most stable carbocation compared to other carbocation i.e.
Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev

Q.16. Heating of 2-chloro-l-phenylbutane with EtOK/EtOH gives X as the major product. Reaction of X with Hg (OAc)2/H2O followed by NaBH4 gives Y as the major product. Y is:    (2019)
(1) Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
(2) Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
(3) Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
(4) Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
Ans.
(3)
Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev

Q.17. An ‘Assertion’ and a ‘Reason’ are given below. Choose the correct answer from the following options :
Assertion (A): Vinyl halides do not undergo nucleophilic substitution easily.
Reason (R): Even though the intermediate carbocation is stabilized by loosely held π-electrons, the cleavage is difficult because of strong bonding.    (2019)
(1) Both (A) and (R) are wrong statements.
(2) Both (A) and (R) are correct statements and (R) is the correct explanation of (A).
(3) Both (A) and (R) are correct statements but (R) is not the correct explanation of (A).
(4) (A) is a correct statement but (R) is a wrong statement.
Ans. 
(4)
Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
Due to partial double bond character of C-halogen bond, halogen leaves with great difficulty, if at all it does. Hence, vinyl halides do not undergo nucleophilic substitution easily. So, assertion is correct.
Previous year Questions (2019-16) - Haloalkanes and Haloarenes JEE Notes | EduRev
Intermediate carbocation is not stabilised by loosely held-π electrons because empty orbital, being at 90°, cannot overlap with p-orbitals of π bond. So, reason is wrong.

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