Reaction Mechanism(11th And 12th > Chemistry ) Questions and Answers
Question 1.
Which of the following statements is incorrect for low reactivity of chloro benzene
Due to resonance
Polarity of C-X bond
sp2 hybridised state of C atom
Due to +E effect of Cl
Explanation:-
Answer: Option D. -> Due to +E effect of Cl : D
Cl is involved in resonance as well as inductive effect and not in electrometric effect as it is more electronegative.
Question 2.
The product in the following reaction is
Explanation:-
Answer: Option A. -> : A
Question 3.
I > II > III
II > I > III
II > III > I
III > II > I
Explanation:-
Answer: Option C. -> II > III > I : C The reactivity decreases in the order
Allylic > Secondary > primary.
Question 4.
The reagent for the above conversion is
Alcoholic KOH
Alcoholic KOH followed by NaNH2
Aqueous KOH followed by NaNH2
Zn/ CH3COOH
Explanation:-
Answer: Option B. -> Alcoholic KOH followed by NaNH2 : B
Question 5.
What is the order of reactivity of the following compounds towards nucleophilic substitution?
IV<III<II<I
IV<I<II<III
III<IV<II<I
II<IV<III<I
Explanation:-
Answer: Option B. -> IV<I<II<III : B
The reactivity depends on the stability of the carbocation obtained upon ionization. The order of stability is .
Question 6.
The major product formed in the following reaction is :
Explanation:-
Answer: Option C. -> : C
In protic solvent E2 proceeds over SN2.
Question 7.
The structure of the major product formed in the following reaction is
Explanation:-
Answer: Option D. -> : D
Alkyl halides are more reactive than aryl halides, therefore the halogen present on the side chain is displaced.
Question 8.
Explanation:-
Answer: Option D. -> : D
Question 9.
The order of decreasing nucleophilicity is
H2O>OH−>CH3COO−>CH3O−
CH3COO−>CH3O−>HO−>H2O
HO−>CH3O−>CH3COO−>H2O
CH3O−>OH−>CH3COO−>H2O
Explanation:-
Answer: Option D. -> CH3O−>OH−>CH3COO−>H2O : D
1. Due to the presence of -ve charge CH3O−, OH−,CH3COO− , are more nucleophilic than H2O. Further due to + I effect of the CH3 group, CH3O− is more nucleophilic than OH−.
2. CH3COO− has the -ve charge on oxygen stabilized by resonance and therefore its nucloephilicity is less than those of CH3O− and OH−.
Question 10.
The rate of SN2 reaction is maximum when the solvent is
CH3OH
H2O
DMSO
Benzene
Explanation:-
Answer: Option C. ->
DMSO
: C
Polar aprotic solvents such as DMSO increase the rate of the SN2 reaction.