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Reaction Mechanism Mcq Neet Chemistry
Quiz 4
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Q.1
In which of the following species the central carbon atom is negativley charged?
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a) Free radical
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b) Carbanion
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c) Carocation
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d) None of these
Explanation
Answer:(b)
Q.2
In the following carbocations, the stability order is
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a) III > II > IV > I
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b) IV > I > II > III
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c) IV > III > II > I
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d) III > IV > II > I
Explanation
Answer:(a)
Q.3
Which of the follwoing is strongest nucleophile?
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a) Br-
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b) :OH-
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c) :CN-
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d) C2H5:-
Explanation
Answer:(d)
Q.4
reaction involving heterolytic fission are sid to produce via
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a) ionic mechanism
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b) polar mechanism
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c) both 9a) and (b)
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d) none of these
Explanation
Answer:(c)
Q.5
Methylene has sextet of electrons around carbon but bears no formal charge Reason: Methylene behaves as a nucleophile
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a) Both Assertion and Reason are true and the Reason is correct explanation of Assertion
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b) Both Assertion and Reason are true but Reason is not the correct explanation of Assertion
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c) Assertion is true, but Reason is false
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d) Assertion and Reason are false
Explanation
Answer:(c)
Q.6
For all practical purposes, influence of inductive effect is neglected after:
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a) 1st carbon atom
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b) 2nd carbon atom
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c) 3nd carbon atom
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d) none of the these
Explanation
Answer:(b)
Q.7
Which of the following species is not electrophilic in nature
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a) Cl+
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b) BH3
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c) H3O+
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d) N+O2
Explanation
Answer:(c)
Q.8
The stabilization due to resonance is maximum iin:
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a) cyclohexane
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b) cyclohexene
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c) 1, 3 -cyclohexadiene
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d) 1, 3, 5 -cyclohexatriene
Explanation
Answer:(d)
Q.9
A free radical is
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a) non existing
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b) short lived
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c) diamagnetic
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d) fairly stable
Explanation
Answer:(b)
Q.10
The order of stability of carbanions is
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a) CH3- > 1° > 2° > 3°
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b) 3° > 2° > 1° > CH3-
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c) 3° > 1° > 2° > CH3-
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d) 2° > 3° > 1° > CH3-
Explanation
Answer:(a)
Q.11
The +I.E. (inductive effect) is shown by
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a) CH3
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b) -OH
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c) F
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d) - C6H5
Explanation
Answer:(a)
Q.12
Hyperconjugation is
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a) σ - π conjugation
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b) noticed due to delocalisation of σ- and π-bonds
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c) no bound resonance
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d) all of the above
Explanation
Answer:(d)
Q.13
Species containing carbon with three bonds and an electron are called
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a) carbanions
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b) free radicals
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c) carbenes
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d) carbocations
Explanation
Answer:(b)
Q.14
Which of the follwoing is an electrophilic reagent?
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a) BF3
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b) RO-
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c)
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d) NH3
Explanation
Answer:(a)
Q.15
Carbanion can undergo
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a) rearrangement
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b) addition to a carbonyl group
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c) combination with cation
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d) substitution reaction at a saturated carbon atom
Explanation
Answer:(e)
Q.16
The shape of
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a) linear
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b) planar
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c) pyramidal
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d) none of these
Explanation
Answer:(c)
Q.17
A neutral divalent carbon intermediate produced by the removal of two attached atoms is called
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a) carbene
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b) carbocation ion
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c) carbanion
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d) free radical
Explanation
Answer:(a)
Q.18
Which of the following statements is not correct
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a) primary carbocations are more stable than secondary ones
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b) Secondary free radicals are more stable than primary free radicals
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c) Tertiary free radicals are more stable than secondary ones
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d) Tertiary carbocations are more stable than primary ones
Explanation
Answer:(a)
Q.19
Which of the following cannot show electromeric effect?
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a) Alkenes
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b) Ketones
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c) Aldehydes
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d) Ethers
Explanation
Answer:(d)
Q.20
The stability of 2, 3-dimethyl but-2-ene iis more than 2-butene. this can be explained in terms of
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a) resonance
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b) hyperconjugation
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c) electromeric effect
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d) inductive effect
Explanation
Answer:(b)
Q.21
Assertion : HC ≡C- is more stable than H2C = C- Reason: HC ≡ C- has more s-character than H2C = C-
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a) Both Assertion and Reason are true and the Reason is correct explanation of Assertion
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b) Both Assertion and Reason are true but Reason is not the correct explanation of Assertion
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c) Assertion is true, but Reason is false
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d) Assertion and Reason are false
Explanation
Answer:(a)
Q.22
Zero inductive effect is shown by
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a) C6H5 -
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b) -H
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c) CH3 -
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d) Cl -
Explanation
Answer:(b)
Q.23
In hyperconjugation, the atom involved is
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a) β- H atom
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b) α- H atom
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c) γ-H atom
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d) all of above
Explanation
Answer:(b)
Q.24
Carbanions initiate
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a) addition reaction
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b) substitution reactions
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c) both (a) and (b)
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d) none of these
Explanation
Answer:(c)
Q.25
What information is provided by reaction mechanism?
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a) The bonds broken and formed
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b) The reaction intermediates
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c) The relative rates of discrete steps, especially the slowest one
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d) all of the above
Explanation
Answer:(d)
Q.26
Shifting of electrons of a multiple bond under the influence of a reagent is called
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a) I-effect
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b) M-effect
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c) M-effect
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d) T-effect
Explanation
Answer:(b)
Q.27
Which group has the maximum -Inductive effect?
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a) -NO2
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b) -CN
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c) -COOH
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d) -F
Explanation
Answer:(a)
Q.28
Which group hsa the highest +Inductive effect?
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a) CH3-
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b) (CH3)3C -
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c) CH3CH2 -
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d) (CH3)3CH -
Explanation
Answer:(b)
Q.29
(CH3)4N+ is neither an electrophile , nor a nucleophile because it
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a) neither has electron pair available for donation nor can accommodate electron since all shells of N are fully occupied
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b) can act as lweis acid
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c) does not have electron pair for donation as well as cannot attract electron pair
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d) none of the above
Explanation
Answer:(a)
Q.30
The -I effect is shown by
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a) -COOH
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b) -CH3
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c) -CH3CH2
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d) -CHR2
Explanation
Answer:(a)
0 h : 0 m : 1 s
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