Test: SN2 Reaction Reactivity


25 Questions MCQ Test Chemistry Class 12 | Test: SN2 Reaction Reactivity


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This mock test of Test: SN2 Reaction Reactivity for Class 12 helps you for every Class 12 entrance exam. This contains 25 Multiple Choice Questions for Class 12 Test: SN2 Reaction Reactivity (mcq) to study with solutions a complete question bank. The solved questions answers in this Test: SN2 Reaction Reactivity quiz give you a good mix of easy questions and tough questions. Class 12 students definitely take this Test: SN2 Reaction Reactivity exercise for a better result in the exam. You can find other Test: SN2 Reaction Reactivity extra questions, long questions & short questions for Class 12 on EduRev as well by searching above.
QUESTION: 1

Only One Option Correct Type

Direction (Q. Nos. 1-12) This section contains 12 multiple choice questions. Each question has four choices (a), (b), (c))and (d), out of which ONLY ONE is correct.

Q. 

Which of the following would be the strongest nucleophile in methanol?

Solution:

Nucleophilicity increases down the group in hydroxylic solvents.

QUESTION: 2

Predict the product in nucleophilic substitution reaction.

Solution:

Inversion of configuration takes place at chiral carbon.

QUESTION: 3

What is the product of the given reaction?

Solution:

 attack at less substituted carbon of epoxide ring from the side opposite to — CH3 group.

QUESTION: 4

Which is the product of the given reaction?

Solution:


QUESTION: 5

What is the major product of the given reaction ?

Solution:

α-carbon is achiral, hence retention of configuration at β-carbon.

QUESTION: 6

Which of the following are the examples of strong nucleophiles but weak base in protic solvents?

I. CH3S-
II. CH3O-
III. I-
IV. H2O
V. F-

Solution:

Both CH3S- and I- are weak bases but strong nucleophiles.

QUESTION: 7

The specific rotation of optically pure (R)-2- butanol is -13.52° at 25°C. An optically pure sample of (R)-2- bromobutane was treated with aqueous NaOH in order to form 2-butanol via SN2 reaction. What would be the specific rotation of the product assuming 100% yield?

Solution:

(S)-2-butanol is formed with specific rotation + 13.52°.

QUESTION: 8

Which of the following correctly describe the relative nucleophilicities of methoxide and tertiary butoxide ion?

Solution:

Although CH3O- is weaker base than (CH3)3CO- , former is stronger nucleophile due to smaller size.

QUESTION: 9

Arrange the following in increasing order of reactivity in an SN2 reaction with K I in acetone solvent.

Solution:

In halogen-exchange (Finkelstein reaction), reactivity is determined by solubility of Na X formed in acetone. Lower the solubility of Na X in acetone, easier the reaction. NaCI is less soluble than NaBr in acetone.

QUESTION: 10

In the following set of nucleophiles, the strongest and the weakest nucleophile respectively are

I. CH3S-
II. CH3COC-
III. HO-
IV. C6H5C-

Solution:

CH3S-(I) is strongest nucleophile and C6H5O-(IV) is weakest due to resonance stabilisation in it.

QUESTION: 11

The major product of the following reaction is:

Solution:

QUESTION: 12

Which of the following on treatment with NaCN (aq) results in an achiral product?

Solution:

*Multiple options can be correct
QUESTION: 13

One or More than One Options Correct Type

Direction (Q. Nos. 13-17) This section contains 5 multiple choice questions. Each question has four choices (a), (b), (c) and (d), out of which ONE or MORE THAN ONE are correct.

Q. 

In which of the following pair(s), the first one is stronger nucleophile than the second one?

Solution:

CH3O- is stronger nucleophile (smaller size) than (CH3)3CO-. HS- is stronger nucleophile than HO- as S is more polarisable than O.

*Multiple options can be correct
QUESTION: 14

In which of the following pair(s), the first one is better leaving group than the second one?

Solution:

Both   are weaker base than its other counterpart.

*Multiple options can be correct
QUESTION: 15

In which of the following reaction, inversion of configuration at chiral carbon takes place?

Solution:

In both option (a) and option (d) α-carbon is chiral, hence SN2 reaction will lead to inversion of configuration. In option (b), α-carbon is achiral, configuration of chiral β-carbon will not be affected. In option (c) SN2 reaction occur twice at the same a-carbon hence, double inversion will give net retention of configuration.

*Multiple options can be correct
QUESTION: 16

Consider the following SN2 reaction,

1-bromobutane + NaCN(aq) → pentanenitrile +NaBr

Q.

Which of the following solvents) when replaces water in the above reaction, increases the rate?

Solution:

All the mentioned solvents are polar and'aprotic, hence increases rate of SN2 reaction.

*Multiple options can be correct
QUESTION: 17

In which of the following reaction(s), reactant and product are correctly matched?

Solution:

In both option (a) and option (c) products have inverted configuration but at α-carbon only. In option (b) product has inverted configuration at both α and β-carbons, hence not true in SN2 reaction. In case of option (d), an equilibrium will be established with K = 1.


At equilibrium both enantiomers exist in equal amounts giving racemic mixture.

QUESTION: 18

Comprehension Type

Direction (Q. Nos. 18-23) This section contains 2 paragraphs, each describing theory, experiments, data, etc. Six questions related to the paragraphs have been given. Each question has only one correct answer among the four given options (a), (b), (c) and (d).

Passage I

In a SN2 reaction, solvent plays a very important role. Hydroxylic solvents like water, alcohols, carboxylic acids etc., solvate nucleophile, decreases its reactivity in the reaction.
Size of donor atom of nucleophile also affect nucleophilicity. A larger donor atom is more easily polarised and less solvated, hence a stronger nucleophile. Therefore, in a given group of periodic table, nucleophilicity increases down the group. However solvation effect is more predominant than polarisability.

Q. 

In water, the order of nucleophilicity of halides is

Solution:

F- is most hydrated, least nucleophilic and I- is most polarisable, strongest nucleophile among halides in H2O.

QUESTION: 19

Passage I

In a SN2 reaction, solvent plays a very important role. Hydroxylic solvents like water, alcohols, carboxylic acids etc., solvate nucleophile, decreases its reactivity in the reaction.
Size of donor atom of nucleophile also affect nucleophilicity. A larger donor atom is more easily polarised and less solvated, hence a stronger nucleophile. Therefore, in a given group of periodic table, nucleophilicity increases down the group. However solvation effect is more predominant than polarisability.

Q. 

In dimethyl sulphoxide (DMSO) solvent, the order of nucleophilicity of haiides ion is

Solution:

In polar aprotic solvent, basicity parallels nucleophilicity.

QUESTION: 20

Passage I

In a SN2 reaction, solvent plays a very important role. Hydroxylic solvents like water, alcohols, carboxylic acids etc., solvate nucleophile, decreases its reactivity in the reaction.
Size of donor atom of nucleophile also affect nucleophilicity. A larger donor atom is more easily polarised and less solvated, hence a stronger nucleophile. Therefore, in a given group of periodic table, nucleophilicity increases down the group. However solvation effect is more predominant than polarisability.

Q. 

Which of the following describe correctly the role of H2O a s solvent in a SN2 reaction?

Solution:

Hydroxylic solvents like H2O , stabilises both nucleophile and transition state, but to a greater extent to nucleophile. As a result, activation energy increases and rate of reaction decreases.

QUESTION: 21

Passage II

In a SN2 reaction, back side attack takes place which leads to inversion of configuration ata-carbon which is known as Walden’s inversion :

Q. 

What is true regarding the follow ing reaction? 

Solution:

The product would have opposite configuration at a-carbon, but reactants and products are not isomers, they are different compounds, have their characteric stereochemical properties not inter-related.

QUESTION: 22

Passage II

In a SN2 reaction, back side attack takes place which leads to inversion of configuration ata-carbon which is known as Walden’s inversion :

Q. 

What can be correctly predicted regarding product of the following reaction ?

Solution:

Both Cl can act as leaving group and there will be equal probability of the two chlorides to leave, giving racemic mixture of products.

QUESTION: 23

Passage II

In a SN2 reaction, back side attack takes place which leads to inversion of configuration ata-carbon which is known as Walden’s inversion :

Q. 

What can be predicted correctly about product of the following SN2 reaction?

Solution:

*Answer can only contain numeric values
QUESTION: 24

One Integer Value Correct Type

Direction (Q. Nos. 24 and 25) This section contains 2 questions. When worked out will result in an integer from 0 to 9 {both inclusive).

Q. 

How many of the following reactions fail to give major product by SN2 reaction as indicated?

 


v . H—C≡C—CH2—CH2I + CH3MgBr → H—C ≡C— CH2— CH2— CH3


Solution:

In (iii), (iv), (v) and (ix); Neutralisation will be preferred over SN2 reaction. In (vi), due to tertiary α-carbon, SN2 is very difficult, however E2 elimination reaction will be preferred in this case.

*Answer can only contain numeric values
QUESTION: 25

In the following reaction,

Q.

How many different dicyano products are expected?


Solution:

Any of the two Cl can be substituted by CN- as:


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