Haloalkanes and Haloarenes Test

Result

Haloalkanes and Haloarenes Test - 27

Score
-
out of -
Rank
-
out of -

TIME Taken - -

SHARING IS CARING

If our Website helped you a little, then kindly spread our voice using Social Networks. Spread our word to your readers, friends, teachers, students & all those close ones who deserve to know what you know now.

Weekly Quiz Competition

Question 1
1 / -0

Ethyl chloride is one of the reactants in:

A
Wurtz reaction

B
Williamson's synthesis

C
Friedel-craft's alkylation

D
All the above

Solution

Ethyl chloride used as a reactant in all the reactions.

Williamson's synthesis: Sodium ethoxide reacts with alkyl halide and ether forms as product.
$$RONa+RX\rightarrow ROR +NaX$$

Wurtz reaction:
$$RX+2Na+RX\rightarrow R-R+2NaX$$

Friedel - Craft alkylation: (as shown in figure)

Option D is correct.
Question 2
1 / -0

Addition of ethanol aqueous, to the benzyl chloride does not increase the rate of the
hydrolysis but changes only the composition of the final products. This indicates that the reaction is proceeding through:

A
$$S_{N}1$$ mechanism

B
$$S_{N}2$$ mechanism

C
$$S_{E}1$$ mechanism

D
$$S_{E}2$$ mechanism

Solution

Rate of $$S_{N}1$$ reactions depends only on one reactant and rate of $$S_{N}2$$ reactions depends on both reactants.
here reaction's rate is depending only on one reactant so it follows $$S_{N}1$$ mechanism.
Question 3
1 / -0

$$S_{N}1$$ reaction is favoured by:

A
non-polar solvents

B
bulky group on the carbon atom attached to the halogen atom

C
small groups on the carbon atom attached to halogen atom

D
all the above

Solution

$$SN^1$$ mechanism proceeds through carbocation formation and as stability of carbocation increases, it favours $$SN^1$$ mechanism.

And as we add bulky group to carbon attached with halogen, carbocation formed will become more stable due to +I effect of bulky alkyl group so it favours $$SN^1$$ mechanism.
Question 4
1 / -0

Which of the following statements are true about $$CHCl_{3}$$?

i) It is used as an anesthetic agent.
ii) It is used as a solvent.
iii) It has $$sp^{2}$$ hybridized carbon.
iv) It has a distorted tetrahedral shape.

The correct statements are:

A
i, ii, iv

B
iii, iv

C
i, ii, iii

D
i, ii

Solution
Question 5
1 / -0

Statement 1: $$S_{N}1$$ reaction is carried out in the presence of polar protic solvents.
Statement 2: Polar protic solvent increases the stability of carbocation due to the solvation.

Read the above statements and choose the correct option regarding it.

A
Statement 1 and Statement 2 are correct and Statement 2 is the correct explanation for Statement 1.

B
Statement 1 and Statement 2 are correct and Statement 2 is not the correct explanation for Statement 1.

C
Statement 1 is correct and Statement 2 is wrong.

D
Statement 1 is wrong and Statement 2 is correct.

Solution

$$SN^1$$ mechanism proceeds through carbocation formation. As the stability of carbocation increases, reaction favours $$SN^1$$ mechanism. Polar protic solvent stabilises carbocation so they favour reaction. In this reaction products formed are racemic mixture.

Option A is correct.
Question 6
1 / -0

Which of the following factors does not favour $$S_{N}1$$ mechanism?

A
Strong nucleophile

B
Polar solvent

C
Low conc. of nucleophile

D
$$3^{0}$$ halide

Solution

$$S_N1$$ mechanism proceeds through carbocation formation, as stability of carbocation increases, reaction favours $$SN^1$$ mechanism.

$$3^0$$ carbocation are more stable than others and also polar solvent increases stability of carbocation so they both favours $$S_N1$$ mechanism.

In $$S_N1$$ reactions, rate of the reaction depends upon the concentration of the substrate only not on the strength of nucleophile.
Question 7
1 / -0

$$C - Cl$$ bond of chlorobenzene in comparison to $$C - Cl$$ bond of methyl chloride is:

A
longer and weaker

B
shorter and weaker

C
shorter and stronger

D
longer and stronger

Solution

The $$C-Cl$$ bond in $$C_6H_5Cl$$ is shorter than in $$CH_3Cl$$ and therefore, stronger.

The lone pair on chlorine are dispersed throughout the benzene ring by resonance. This gives the $$C-Cl$$ bond a double bond character.

Option C is correct.
Question 8
1 / -0

The IUPAC name of chloretone is :

A
Trichloroacetone.

B
Trichloronitromethane.

C
1,1,1-Trichloro-2-methyl-2-propanone.

D
1,1,1-Trichloro-2-methyl-2-propanol.

Solution

IUPAC name of chloretone is 1,1,1-Trichloro-$$2$$-methyl-$$2$$-propanol.

Hence, the correct option is D.
Question 9
1 / -0

Which of the following is not true for $$S_{N}1$$ reactions ?

A
These occur through a single step.

B
These are favoured by polar solvents.

C
$$3^{o}$$ alkyl halides generally react through this mechanism.

D
Concentration of nucleophile does not affect the rate of such reactions.

Solution

The mechanism above shows a $$S_N1$$ reaction.
The first step involves the slow loss of leaving group $$L$$ giving a carbocation. In the second step, attack by nucleophile $$(Nu^-)$$ occurs on the carbon centre of carbocation.

$$S_N1$$ mechanism proceeds through carbocation formation and so, it is a two-step process and like the stability of carbocation increases, reaction favours $$S_N1$$ mechanism. This is because the formation of the carbocation is a slow and rate-determining step.

Thus, the greater is the stability of carbocation, greater will be the possibility of its formation and hence, greater will be the rate.

$$3^o$$ carbocations are more stable than others due to the electron donating effect of three alkyl groups. Polar solvents also increases the stability of carbocation by surrounding it through negative ends. Concentration of nucleophile does not affect the rate of such reactions.

Hence, the statement that the $$S_N1$$ reactions occur through a single step is incorrect.

$$\therefore$$ Option A is the correct answer.

Question 10

1 / -0

The correct match is :

	List-I		List-II
A	$$C_2H_5Cl$$	1	Williamson synthesis
B	R-X+Mg+dry ether	2	Wurtz reaction
C	$$C_2H_5Cl+C_2H_5ONa$$	3	Anaesthetic
D	Na+dry ether	4	Antiseptic
		5	Grignard reagent

$$A-3, B-5, C-1, D-2$$

$$A-5, B-3, C-1, D-2$$

$$A-3, B-4, C-1, D-2$$

$$A-3, B-5, C-1, D-4$$

Solution

Wurtz reaction:
$$R-X+2Na+R-X\rightarrow R-R+2NaX$$
Grignard reaction:
$$R-X+Mg\xrightarrow {dry ether} R-Mg-X$$
Williamson's synthesis:
$$C_2H_5Cl+C_2H_5ONa\rightarrow C_2H_5OC_2H_5$$ and
$$C_2H_5Cl$$ is anaesthatic .

User

Question Analysis

Correct -
Wrong -
Skipped -

My Perfomance

Score
-
out of -
Rank
-
out of -

Re-Attempt Weekly Quiz Competition

Haloalkanes and Haloarenes Test - 27

Result

Haloalkanes and Haloarenes Test - 27

Score

-

Rank

-

SHARING IS CARING

Question 1

Wurtz reaction

Williamson's synthesis

Friedel-craft's alkylation

All the above

Solution

Question 2

$$S_{N}1$$ mechanism

$$S_{N}2$$ mechanism

$$S_{E}1$$ mechanism

$$S_{E}2$$ mechanism

Solution

Question 3

non-polar solvents

bulky group on the carbon atom attached to the halogen atom

small groups on the carbon atom attached to halogen atom

all the above

Solution

Question 4

i, ii, iv

iii, iv

i, ii, iii

i, ii

Solution

Question 5

Statement 1 and Statement 2 are correct and Statement 2 is the correct explanation for Statement 1.

Statement 1 and Statement 2 are correct and Statement 2 is not the correct explanation for Statement 1.

Statement 1 is correct and Statement 2 is wrong.

Statement 1 is wrong and Statement 2 is correct.

Solution

Question 6

Strong nucleophile

Polar solvent

Low conc. of nucleophile

$$3^{0}$$ halide

Solution

Question 7

longer and weaker

shorter and weaker

shorter and stronger

longer and stronger

Solution

Question 8

Trichloroacetone.

Trichloronitromethane.

1,1,1-Trichloro-2-methyl-2-propanone.

1,1,1-Trichloro-2-methyl-2-propanol.

Solution

Question 9

These occur through a single step.

These are favoured by polar solvents.

$$3^{o}$$ alkyl halides generally react through this mechanism.

Concentration of nucleophile does not affect the rate of such reactions.

Solution

Question 10

$$A-3, B-5, C-1, D-2$$

$$A-5, B-3, C-1, D-2$$

$$A-3, B-4, C-1, D-2$$

$$A-3, B-5, C-1, D-4$$

Solution

User

Question Analysis

My Perfomance

Score

-

Rank

-

Results Announcement on: coming Monday

Stay Tuned: We’ll update you on your result via email or SMS.