Reaction Mechanism of Analysis MCQ with Answers for IIT JAM 2023

Reaction Mechanism of Analysis MCQ with Answers for IIT JAM 2023

IIT JAM 2022 Chemistry MCQs with Answers of Reaction Mechanism

Reaction Mechanism of Analysis MCQ with Answers for IIT JAM 2023


1. Aryl halides are less reactive towards nucleophilic substitution reactions as compared to alkyl halides due to

(a) The formation of less stable carbanion
(b) Longer carbon halogen bond
(c) The inductive effect
(d) spa-hybridized carbon attached to the halogen

Answer

Answer: (d)


2. Which of the following statement (s) is/are correct

(a) E2 is a concerted reaction in which bonds break and new bonds form at the same time in a single step.
(b) Order of reactivity of alkyl halides towards E2 dehydrohalogenation is found to be 3° > 2°> 1°
(c) In E2 reaction both B hydrogen and leaving group should be antiperiplanar.
(d) In E2 elimination different stereoisomer (diastereomer) converts into a different stereo product.

Answer

Answer: (a,b,c,d)


3. Which is/are correct about alkyl bromide having molecular formula C5H11Br

(a) One isomeric alkyl bromide undergoes E1 elimination at the fastest rate.
(b) Only one is incapable of reacting by the E2 mechanism
(c) Only one isomer gives a single alkene on E2 elimination
(d) 2-Bromopentane gives the most complex mixture of alkenes on E2 elimination

Answer

Answer: (a,b,d)


4. Which of the following order is/are correct for the rate of E2 reaction?


(a) 5-Bromocycloheptene > 4-Bromocycloheptene
(b) 2-Bromo-1-phenylbutane > 3-Bromo-l-phenylbutane
(c) 3-Bromocyclohexene > Bromocyclohexane.
(d) 3-Bromo-2-methylpentane > 2-Bromo-4-methylpentane

Answer

Answer: (b,c,d)


5. The smallest compound, which on photochlorination produces diastereomers is

(a) 3-methyl, 3-chloro hexane
(b) 2-chloro butane
(c) 1-bromo propane
(d) 1-bromo-3-methyl butane

Answer

Answer: (b)


6. When (1R, 2R)-1, 2-Dibromo-1, 2-diphenyl ethane is treated with an alcoholic solution of KOH, the most probable product would be :

(a) trans-1, 2-diphenyl ethene
(b) A mixture of a cis, trans alkenyl bromide
(c) cis-alkenyl bromide
(d) trans-alkenyl bromide (with respect to phenyl)

Answer

Answer: (d)


7. When Nitrobenzene is treated with Br2 in presence of FeBr3 the major product formed is m-bromonitro benzene. Statements that are related to obtaining m-isomer are:

(a) The electron density on meta carbon is more than that on ortho and para positions.
(b) The intermediate carbonium ion formed after the initial attack of Br+ at the metà position is least destabilized.
(c) Loss of aromaticity when Br+ attacks at the ortho and para positions, not at the meta position
(d) Easier loss of H+ to regain aromaticity from the meta position than from ortho and para positions.

Answer

Answer: (b)


8. Which of these statements is correct about nucleophiles :

(a) Nucleophiles have an unshared electron pair and can make use of this to react with an electron-deficient species.
(b) The nucleophilicity of an element (as an electron donor) generally increases on going down a group in the periodic table.
(c) A nucleophile is electron-deficient species
(d) All good nucleophiles are good bases when we deal across the period.

Answer

Answer: (a,b,d)


9. Which of the following is I are true for SN1 reactions?

(a) They occur through a single-step concerted reaction.
(b) They are favored by polar solvents.
(c) 3° alkyl halides generally react through this mechanism.
(d) Concentration of nucleophiles does not affect the rate of such reactions.

Answer

Answer: (b)


10. Which of the following statements is/are correct for alkyl halide?

(a) In most unimolecular reactions of alkyl halide SN1 reaction is favored over E1 reaction.
(b) E1 mechanism is favored as compared to SN1mechanism by branching at ß carbon
(c) In unimolecular reaction, increasing the temperature favors. E1 mechanism
(d) E1 reactions are favored by the use of weak bases and by the use of polar solvents.

Answer

Answer: (a)


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