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Test: Reaction Intermediate Level - 1 - Chemistry MCQ


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30 Questions MCQ Test Organic Chemistry - Test: Reaction Intermediate Level - 1

Test: Reaction Intermediate Level - 1 for Chemistry 2024 is part of Organic Chemistry preparation. The Test: Reaction Intermediate Level - 1 questions and answers have been prepared according to the Chemistry exam syllabus.The Test: Reaction Intermediate Level - 1 MCQs are made for Chemistry 2024 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests for Test: Reaction Intermediate Level - 1 below.
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Test: Reaction Intermediate Level - 1 - Question 1

Which of the following is most reactive as a nucleophile?

Detailed Solution for Test: Reaction Intermediate Level - 1 - Question 1

The most nucleophile is dependent on the compound which has a tendency to give an electron. In the compound there is oxygen and one has sulphur. The sulphur has big in size that why it has more tendency to donate an electron. The correct answer is PhS-

Test: Reaction Intermediate Level - 1 - Question 2

 Reactivity of the following towards reaction with LiAlH4 is:

   
 

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Test: Reaction Intermediate Level - 1 - Question 3

 The relative acidity of the indicated H in each of the following is:

  
 

Test: Reaction Intermediate Level - 1 - Question 4

Detailed Solution for Test: Reaction Intermediate Level - 1 - Question 4

Test: Reaction Intermediate Level - 1 - Question 5

 The relative nucleophilicity in polar, protic, solvents of the following is:
 

Detailed Solution for Test: Reaction Intermediate Level - 1 - Question 5

Correct Answer :- a

Explanation : In a polar protic solvent (CH3OH), nucleophilicity increases down a column of the periodic table. So S- is more nucleophilic than O-.

For two species with the same attacking atom, the more basic is the more nucleophilic, so CH3CH2O- is more nucleophilic than CH3CO2-

CO2- give identical str resonance hybrids more solvated, very less nucleophilic.

Test: Reaction Intermediate Level - 1 - Question 6

The acidity of the protons H in each of the following is:
  

Test: Reaction Intermediate Level - 1 - Question 7

The relative nucleophilicity in polar, protic, solvents of the following is:
  (I) CH3OH                  (II) CH3SH                (III) CH3NH2
 

Test: Reaction Intermediate Level - 1 - Question 8

Reactivity of the following towards reaction with NaBH4 is:

Test: Reaction Intermediate Level - 1 - Question 9

 Rate of reaction of CH3COCl/AlCl3 with each of the following is:


 

Test: Reaction Intermediate Level - 1 - Question 10

 Identify correct C—O bond length order:

Detailed Solution for Test: Reaction Intermediate Level - 1 - Question 10

I is the shortest because of double bond.

III is next because of resonance.

II is last as there is no kind of bond strengthening.

Hence, B is correct.

Test: Reaction Intermediate Level - 1 - Question 11

 The resonance energy of each of the following is:

Detailed Solution for Test: Reaction Intermediate Level - 1 - Question 11

Correct Answer :- d

Explanation : Resonance energy per ring decreases as ring size increases

So, III > I > II (Resonance energy/ring)

Anthracene>Benzene>Naphthalene.

Test: Reaction Intermediate Level - 1 - Question 12

Identify order of per ring resonance energies of each of the following:

Test: Reaction Intermediate Level - 1 - Question 13

 The relative stability of the following carbocations is:

Detailed Solution for Test: Reaction Intermediate Level - 1 - Question 13

Correct Answer :- d

Explanation : The dispersal of the charge stabilizes the carbocation. More the number of alkyl groups, the greater the dispersal of positive charge and therefore, more the stability of carbocation,is an electron donating group, thus it will increases the stability of carbocation, hence the expected order is, (iii)>(ii)>(i).

Test: Reaction Intermediate Level - 1 - Question 14

Which of the following systems are resonance contributions of the radical shown below:

Detailed Solution for Test: Reaction Intermediate Level - 1 - Question 14

Since, a free radical does the homolysis of pi bond.
The adjacent free radicals later form a bend.

Test: Reaction Intermediate Level - 1 - Question 15

 Imidazole has a pKa = 7 with respect to its conjugate acid. Which N is protonated in this conjugate acid and why?

Test: Reaction Intermediate Level - 1 - Question 16

 Cyclopentadiene has a pKa = 15, whereas cyclopentane has a pKa > 50. This is because:
 

Detailed Solution for Test: Reaction Intermediate Level - 1 - Question 16

Since after deprotonation cyclopentadiene becomes stable by aromaticity, So, it will definitely have a higher acidic strength than that of cyclopentane and consequently lower pKa value.

Further, no such stability factor has a role in the case of cyclopentane so it has lower acidic strength comparatively.

Test: Reaction Intermediate Level - 1 - Question 17

Which of the following is most likely to undergo a favourable hydride shift?
 

Detailed Solution for Test: Reaction Intermediate Level - 1 - Question 17

Test: Reaction Intermediate Level - 1 - Question 18

Arrange the following intermediate into decreasing order of stability.

Detailed Solution for Test: Reaction Intermediate Level - 1 - Question 18

Test: Reaction Intermediate Level - 1 - Question 19

Which of the following forms most stable carbocation upon removal of OH–:
 

Test: Reaction Intermediate Level - 1 - Question 20

 Which of the following carbonium ion is most stable?
 

Detailed Solution for Test: Reaction Intermediate Level - 1 - Question 20

A is the correct option as 9- alpha Hydrogens are present. More alpha hydrogen, more hyperconjugation, more stability.

Test: Reaction Intermediate Level - 1 - Question 21

Which of the following carbocations would not likely rearrange to a more stable carbocation?
 

Test: Reaction Intermediate Level - 1 - Question 22

 Which carbocation is the most stabilized:
 

Test: Reaction Intermediate Level - 1 - Question 23

Which one of the following carbocation would you expect a H migration?

Detailed Solution for Test: Reaction Intermediate Level - 1 - Question 23

In option B and C, after carbocation rearrangement, it will remain 2°, therefore, rearrangement will not take place.
In option D, after carbocation rearrangement 3° will become 2° or 1°, therefore, rearrangement will not take place.
In option A, after rearrangement, carbocation will become 3° from 2°, therefore, this rearrangment will take place.

Test: Reaction Intermediate Level - 1 - Question 24

Which carbocation is the most stable?
 

Test: Reaction Intermediate Level - 1 - Question 25

 Arrange stability of the given carbocations in decreasing order:

Detailed Solution for Test: Reaction Intermediate Level - 1 - Question 25

Correct Answer :- c

Explanation : The carbocation here is stabilized when there is an electron-donating group present.

More the activating effect of the group, more stable is the cation. Out of given options, I is most stable due to ability of oxygen to activate the ring with its lone pair of electrons.

Out of III and I,III is more stable as the lone pair of nitrogen in II is less available due to Ac group. IV is least stable due to electron- withdrawing effect of Cl atom.

The correct answer is : IV < II < III < I

Test: Reaction Intermediate Level - 1 - Question 26

Which intermediate is involved in the reaction given below?

Detailed Solution for Test: Reaction Intermediate Level - 1 - Question 26

Ans: d

Explanation: As we can see, the first step in the presence of light carbene is formed.

organic-chemistry-questions-answers-reaction-intermediates-q5a

Test: Reaction Intermediate Level - 1 - Question 27

 Consider the following statements:
 

Test: Reaction Intermediate Level - 1 - Question 28

 Which is the most stable arenium carbocation:
 

Test: Reaction Intermediate Level - 1 - Question 29

 Which of the following statements is correct:

Test: Reaction Intermediate Level - 1 - Question 30

 List the following carbocations in order of decreasing stability (starting with the most stable):

Detailed Solution for Test: Reaction Intermediate Level - 1 - Question 30

Correct Answer :- b

Explanation : I have an sp2 hybridized carbocation which is highly unstable. Hence, I will be the least stable of all. III will be the most stable as it is tertiary carbocation.

Among II and IV, IV has 4 alpha− hydrogens whereas II has only, α− hydrogens. Also IV is a secondary carbocation while II is a primary one. Hence IV will be more stable than II.

Hence, the decreasing order of stability or stabilization energy is III>IV>II>I

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