How Do We Decide between the SN1 and SN2 Mechanisms

Q. The order of reactivities of the following alkyl halides for a $S_{N}2$ reaction is

1. RI > RBr > RCl > RF
2. RF > RBr > RCl > RI
3. RF > RCl > RBr > RI
4. RCl > RBr > RF > RI

Q.

Give the products formed when:

When ethyl chloride is treated with aqueous $\mathrm{KOH}$__________.

Q. Which of the following compound readily undergo both $S_{N}1$ and $S_{N}2$ reaction?

1. 
2. 
3. 
4. None of the above

Q. For the following compounds, the correct statement(s) with respect to nucleophilic substitution reactions is(are)

1. I and III follow $S_{N}1$ mechanism
2. I and II follow $S_{N}2$ mechanism
3. Compound IV undergoes inversion of configuration
4. The order of reactivity for I, III and IV is: IV > I > III

Q. What is the function of anhydous $ZnC{l}_2$ in Lucas test for distinction between $1^o,2^o\text{and}{3}^o$ alcohols?

1. act as nucleophile
2. act as dehydrating agent
3. act as lewis base
4. act as lewis acid

Q. 1.Whats mean by pseudo unimolecular reaction ñ

Q.
The rates $r_1,r_2$ and $r_3$ are in the order:

1. $r_1>r_2>r_3$
2. $r_3>r_1>r_2$
3. $r_1>r_3>r_2$
4. $r_2>r_1>r_3$

Q. The major product P for the given reaction is :

1. 
2. 
3. 
4. 

Q. The increasing order of reactivity of the following compounds in $S_{N}2$ reaction is

1. $C_6{H}_5{\mathrm{CH}}_2\mathrm{Br}$
2. $C_6{H}_5\mathrm{CH}\left(C_6{H}_5\right)\mathrm{Br}$
3. $C_6{H}_5\mathrm{CH}\left({\mathrm{CH}}_3\right)\mathrm{Br}$
4. $C_6{H}_{5}C\left({\mathrm{CH}}_3\right)\left(C_6{H}_5\right)\mathrm{Br}$

Q. Which of the following reactions proceeds through concerted mechanism?

1. Nucleophilic Substitution unimolecular
2. Nucleophilic Substitution bimolecular
3. Both (a) and (b)
4. Neither (a) nor (b)

Q. Propose product with a appropriate stereochemistry in the following $S_{N}2$ reaction.

1. 
2. 
3. 
4. 

Q. Which type of elimination takes place when 2-phenylethylbromide heated with NaOEt ?

1. El elimination
2. E2 elimination
3. ElcB elimination
4. E2 or E1cB

Q.

Write the equation for the conversion of ethyne to benzene

Q.

Which of the following halides will be most reactive in $S{N}^2$ reaction and $S{N}^1$ reaction, respectively?

1. (III), (I)

2. (I), (III)

3. (II), (I)

4. (I), (II)

Q. what is difference in pseudo unimolecular and pseudo first order reaction?

Q.
The above reaction results in 98% racemization, the reaction mainly follows:

1. $S_{N}1\text{mechanism}$
2. $S_{N}2\text{mechanism}$
3. Can be both $S_{N}1$ and $S_{N}2$
4. Neither $S_{N}1$ nor $S_{N}2$

Q.

The increasing order of the reactivity of the following halides for the ${\mathrm{S}}_{\mathrm{N}}1$ reaction is :

1. $\left(\mathrm{I})<(\mathrm{III})<(\mathrm{II}\right)$

2. $\left(\mathrm{II})<(\mathrm{III})<(\mathrm{I}\right)$

3. $\left(\mathrm{III})<(\mathrm{II})<(\mathrm{I}\right)$

4. $\left(\mathrm{II})<(\mathrm{I})<(\mathrm{III}\right)$

Q. Which is the incorrect order of relative reactivity of Alkyl halide?

1. $S_{N}1\to$ tertiary > secondary > primary
2. $E1\to$ tertiary > secondary > primary
3. $E2\to$ primary > secondary > tertiary
4. $S_{N}2\to$ primary > secondary > tertiary

Q. Arrange the following compounds in decreasing order of rate for nucleophilic addition reaction.
(X) $CC{l}_{3}CHO$ (Y) $C{H}_{3}CHO$
(Z) $C{H}_{3}COC{H}_3$ (W) $C{F}_{3}CHO$

1. W > Z > X > Y
2. W > X > Y > Z
3. W > Y > Z > X
4. W > Z > Y > X

Q. Which one of the following halogen compounds is difficult to be hydrolysed by $S_{N}1$ mechanism?

1. Chlorobenzene
2. Isopropyl chloride
3. Tertiary butyl chloride
4. Benzyl chloride

Q.
The major product obtained when this substrate is subjected to $E_2$ reaction will be

1. 
2. 
3. Both (A) and (B)
4. None of these

Q. The correct order of reactivity of following compounds in $S_{N}1$ reaction is :

1. $d>b>c>a$
2. $a>b>c>d$
3. $d>c>b>a$
4. $a>c>d>b$

Q.
The major product obtained when this substrate is subjected to $E_2$ reaction will be

1. 
2. 
3. Both (A) and (B)
4. None of these

Q. Which of the following do not show tautomerism?

1. Nitrobenzene
2. m-dinitrobenzene
3. Nitroethane
4. Both $A$ and $B$

Q.

Consider the following reactions:

$I.M{e}_{3}C-Cl\stackrel{\stackrel{\ominus }{OH}}{\to }M{e}_{3}C-OHII.F_{3}C-\underset{\underset{Me}{|}}{CH}-Cl\stackrel{\stackrel{\ominus }{OH}}{\to }{F}_{3}C-\underset{\underset{Me}{|}}{CH}-OHIII.M{e}_{3}C-Cl\stackrel{90\%D_{2}O+10\%ether}{\to }M{e}_{3}C-ODIV.M{e}_{3}C-Cl\stackrel{90\%H_{2}O+10\%ether}{\to }M{e}_{3}C-OH$

Which of the following statements are correct?

1. Reaction (I) is faster than (II).

2. Reaction (II) is faster than (I).

3. Reaction (III) is faster than (IV).

4. Reaction (IV) is faster than (III).

Q.

Is it that for both E1 and E2 mechanisms order of reactivity is

3^o​​​​ > 2^o > 1^o​​​ carbocation

Q. Acid on reaction with alcohol form ester, this reaction is called esterification. Esterification may be intermolecular or intramolecular. Select the compound which will not show esterification reaction with $H^{+}\Delta$.

1. 
2. 
3. 
4. 

Q. Which of the following pair of mechanisms is correct for the given reactions?
$C{H}_3-C{H}_2-C{H}_2-Br\underset{△}{\overset{C{H}_{3}C{H}_{2}OH/C{H}_{3}C{H}_2{O}^{-}}{\to }}C{H}_3-CH=C{H}_2$
$H_{3}C-CH\left(Br\right)-C{H}_3\underset{△}{\overset{C{H}_{3}C{H}_{2}OH/H_{2}O}{\to }}C{H}_3-CH=C{H}_2$

1. $S_{N}1,E1$
2. $S_{N}2,E2$
3. $E2,E1$
4. $S_{N}1,S_{N}2$

Q. Which of the following reactions are both stereospecific and stereoselective?

1. $S_{N}1$
2. $S_{N}2$
3. $E_1$
4. $E_2$

Q. The increasing order of reactivity of the substrates for $S_{N}1$ reaction is

1. $\mathrm{Benzyl}\mathrm{chloride}$
2. $\mathrm{Tert}-\mathrm{butylchloride}$
3. $\mathrm{Allyl}\mathrm{chloride}$
4. $\mathrm{Ethylchloride}$