Question 1

In the reaction of 1-bromobutane with KOH in alcoholic solution, the major product is:

Accepted Answer

Alcoholic KOH promotes elimination (E2 reaction) rather than substitution, producing 1-butene as the major product from a primary haloalkane.

Question 2

Which of the following haloalkanes undergoes SN2 reaction most readily?

Accepted Answer

Primary haloalkanes are most reactive in SN2 reactions due to least steric hindrance around the carbon bearing the halogen.

Question 3

What is the IUPAC name of the compound CH₃CHBrCH₂CH₃?

Accepted Answer

The main chain has 4 carbons (butane), and the bromine is attached to carbon 2 when numbered from the nearest end, giving 2-bromobutane.

Question 4

Which haloarene is most resistant to nucleophilic aromatic substitution?

Accepted Answer

The methoxy group (-OCH₃) is an electron-donating group that increases electron density on the benzene ring, making the C-Cl bond stronger and more resistant to nucleophilic attack.

Question 5

Which of the following statements about haloarenes is correct?

Accepted Answer

The C-X bond in haloarenes is shorter and stronger due to sp² hybridization of the aromatic carbon, making haloarenes less reactive towards nucleophilic substitution.

Question 6

Which of the following haloalkanes undergoes SN1 reaction most readily?

Accepted Answer

Tertiary haloalkanes form the most stable carbocation intermediate, favoring SN1 mechanism.

Question 7

What is the product when chlorobenzene reacts with NaOH at high temperature and pressure?

Accepted Answer

Nucleophilic aromatic substitution of chlorobenzene with NaOH under forcing conditions (high T and P) produces phenol and NaCl.

Question 8

Which statement about the C-X bond in haloalkanes is correct?

Accepted Answer

The C-I bond is the weakest among C-halogen bonds due to poor orbital overlap with the large iodine atom, making it most easily broken.

Question 9

In the Wurtz reaction, 1-bromobutane reacts with Na in dry ether to form the major product as:

Accepted Answer

Wurtz reaction couples two alkyl halide molecules; two molecules of 1-bromobutane couple to form octane (C8H18).

Question 10

Which haloarene is most easily prepared by direct halogenation of benzene?

Accepted Answer

Chlorobenzene is most readily formed by electrophilic aromatic substitution of benzene with Cl2 in the presence of FeCl3 catalyst.

Question 11

In the reaction of 1-bromopropane with KOH in alcoholic solution, the major product formed is:

Accepted Answer

Alcoholic KOH favors elimination (E2) over substitution, producing propene as the major product.

Question 12

Which of the following haloalkanes has the highest boiling point?

Accepted Answer

CH3I has the highest boiling point due to the largest molecular size and strongest London dispersion forces among methyl halides.

Question 13

What is the IUPAC name of the compound CHCl3?

Accepted Answer

The IUPAC name follows the format of naming the parent alkane with halogen substituents; CHCl3 is trichloromethane.

Question 14

In the preparation of chlorobenzene from benzene using Cl2 and FeCl3 catalyst, the reaction is classified as:

Accepted Answer

Halogenation of benzene is an electrophilic aromatic substitution where Cl+ attacks the electron-rich benzene ring with FeCl3 activating Cl2 to form electrophile.

Question 15

Which of the following haloalkanes undergoes SN1 reaction most readily?

Accepted Answer

Tertiary haloalkanes form the most stable carbocation intermediate, making SN1 reaction fastest; (CH3)3C-Br is a tertiary bromide.

Question 16

The boiling point of chloroform (CHCl3) is higher than that of dichloromethane (CH2Cl2) because:

Accepted Answer

Chloroform's C-H bond acts as a hydrogen bond donor to the lone pairs on Cl atoms of adjacent molecules, creating stronger intermolecular forces than van der Waals forces alone in dichloromethane.

Agniveer (All) Haloalkanes & Haloarenes

Haloalkanes & Haloarenes — Practice Questions