Q.1 Which of the following is a primary haloalkane?
CH3CH2Cl
CH3CHClCH3
CCl4
CH3CCl3
Explanation - A primary haloalkane has the halogen attached to a carbon which is bonded to only one other carbon. In CH3CH2Cl, Cl is attached to a primary carbon.
Correct answer is: CH3CH2Cl
Q.2 Which reagent is commonly used for the halogenation of benzene to form chlorobenzene?
Cl2/FeCl3
Br2/FeBr3
HCl/AlCl3
Cl2/UV light
Explanation - Chlorobenzene is formed by electrophilic substitution of benzene using Cl2 in the presence of FeCl3 as a catalyst.
Correct answer is: Cl2/FeCl3
Q.3 Which of the following undergoes SN1 reaction most readily?
CH3CH2Cl
CH3CClCH3
CCl4
CH3CH2CH2Cl
Explanation - Tertiary haloalkanes undergo SN1 reactions fastest because the carbocation formed is stabilized by alkyl groups. CH3CClCH3 is secondary and more reactive than primary.
Correct answer is: CH3CClCH3
Q.4 What type of isomerism is shown by C2H5Cl and CH3CH2Cl?
Chain isomerism
Positional isomerism
Functional isomerism
No isomerism
Explanation - Both molecules represent the same compound, ethyl chloride. There is no isomerism between them.
Correct answer is: No isomerism
Q.5 Which of the following haloalkanes is most reactive towards nucleophilic substitution?
CH3CH2I
CH3CH2Br
CH3CH2Cl
CH3CH2F
Explanation - Reactivity in nucleophilic substitution increases with the size of the halogen due to weaker C–X bond. Iodides react fastest.
Correct answer is: CH3CH2I
Q.6 Which of the following is an example of a haloarene?
CH3CH2Cl
C6H5Cl
CH3CCl3
CH3CH2Br
Explanation - Haloarenes are aromatic compounds with halogen attached to the benzene ring. C6H5Cl is chlorobenzene.
Correct answer is: C6H5Cl
Q.7 Which halide reacts with aqueous AgNO3 fastest?
CH3Cl
CH3Br
CH3I
CH3F
Explanation - The reaction rate of haloalkanes with AgNO3 in ethanol increases with increasing C–X bond length. Iodides react fastest.
Correct answer is: CH3I
Q.8 Which of the following reactions is characteristic of haloarenes?
Free radical substitution
Nucleophilic substitution
Electrophilic substitution
Elimination reaction
Explanation - Haloarenes typically undergo electrophilic substitution rather than nucleophilic substitution due to the stability of the aromatic ring.
Correct answer is: Electrophilic substitution
Q.9 Which of the following undergoes SN2 reaction most readily?
CH3CH2Cl
CH3CHClCH3
CCl4
CH3CCl3
Explanation - Primary haloalkanes react faster in SN2 reactions due to less steric hindrance. CH3CH2Cl is primary.
Correct answer is: CH3CH2Cl
Q.10 Which halogenated compound is commonly used as a dry cleaning solvent?
CCl4
CH3Cl
C2H5Br
CH3CH2Cl
Explanation - Carbon tetrachloride (CCl4) was historically used as a dry cleaning solvent and fire extinguisher.
Correct answer is: CCl4
Q.11 Which of the following is a tertiary haloalkane?
CH3CH2CH2Cl
CH3CCl3
(CH3)3CCl
CH3CHClCH3
Explanation - A tertiary haloalkane has the halogen attached to a carbon bonded to three other carbons. (CH3)3CCl fits this criterion.
Correct answer is: (CH3)3CCl
Q.12 Which reaction occurs when chlorobenzene is treated with NaOH at high temperature and pressure?
SN1 reaction
SN2 reaction
Nucleophilic aromatic substitution
Electrophilic substitution
Explanation - Chlorobenzene reacts with NaOH under harsh conditions via nucleophilic aromatic substitution to form phenol.
Correct answer is: Nucleophilic aromatic substitution
Q.13 Which property increases as the number of halogen atoms in a haloalkane increases?
Boiling point
Solubility in water
Volatility
Reactivity with nucleophiles
Explanation - More halogen atoms increase molecular weight and van der Waals forces, leading to higher boiling points.
Correct answer is: Boiling point
Q.14 Which of the following is formed when benzene reacts with Br2 in the presence of FeBr3?
Bromobenzene
1,2-Dibromobenzene
Benzyl bromide
Bromocyclohexane
Explanation - Electrophilic bromination of benzene in the presence of FeBr3 forms bromobenzene.
Correct answer is: Bromobenzene
Q.15 Which haloalkane is used as a refrigerant?
CHClF2 (Freon-22)
CH3CH2Cl
CCl4
CH3CH2Br
Explanation - CHClF2, also known as Freon-22, is widely used in refrigeration systems.
Correct answer is: CHClF2 (Freon-22)
Q.16 Which of the following is an allylic halide?
CH2=CHCH2Cl
CH3CH2Cl
CCl4
CH3CCl3
Explanation - An allylic halide has the halogen attached to a carbon adjacent to a C=C bond. CH2=CHCH2Cl fits this definition.
Correct answer is: CH2=CHCH2Cl
Q.17 Which halogen in haloalkanes makes them least reactive towards SN2 reactions?
F
Cl
Br
I
Explanation - Fluorides have very strong C–F bonds, making them less reactive in SN2 reactions.
Correct answer is: F
Q.18 Which reagent converts an alcohol into a chloroalkane?
PCl5
NaOH
H2SO4
KMnO4
Explanation - PCl5 reacts with alcohols to replace –OH with –Cl, forming chloroalkanes.
Correct answer is: PCl5
Q.19 Which compound is expected to have the highest boiling point?
CH3CH2Cl
CH3CH2Br
CH3CH2I
CH3CH2F
Explanation - Boiling point increases with molecular weight and polarizability. CH3CH2I has the heaviest halogen and thus highest boiling point.
Correct answer is: CH3CH2I
Q.20 Which of the following haloarenes is most reactive towards nucleophilic substitution?
C6H5F
C6H5Cl
C6H5Br
C6H5I
Explanation - In nucleophilic aromatic substitution, C–F bond is highly polarized, making fluorobenzene more reactive despite bond strength.
Correct answer is: C6H5F
Q.21 Which of the following is used as a solvent in organic reactions?
CH2Cl2
CH3Cl
CCl4
CH3CCl3
Explanation - Dichloromethane (CH2Cl2) is commonly used as a solvent in organic chemistry due to its moderate polarity and volatility.
Correct answer is: CH2Cl2
Q.22 Which reaction converts an alkyl halide into an alkene?
Elimination reaction with KOH
Addition reaction with HBr
Substitution with NaOH
Reduction with LiAlH4
Explanation - Alkyl halides undergo elimination with alcoholic KOH to form alkenes (dehydrohalogenation).
Correct answer is: Elimination reaction with KOH
Q.23 Which of the following is a benzylic halide?
C6H5CH2Cl
C6H5Cl
CH3CH2Cl
CH3CCl3
Explanation - A benzylic halide has the halogen attached to the carbon next to a benzene ring. C6H5CH2Cl is a benzylic halide.
Correct answer is: C6H5CH2Cl
Q.24 Which reaction occurs when haloarenes are heated with aqueous KOH in a sealed tube?
Formation of phenol
Formation of alcohol
Formation of ether
No reaction
Explanation - Under high temperature and pressure, halobenzenes react with KOH to form phenols via nucleophilic aromatic substitution.
Correct answer is: Formation of phenol
Q.25 Which of the following is true about haloalkanes?
They are generally polar due to the C–X bond
They are non-polar
They do not undergo substitution reactions
They are strong acids
Explanation - C–X bonds are polar due to the difference in electronegativity between carbon and halogen, making haloalkanes polar.
Correct answer is: They are generally polar due to the C–X bond