Organic Chemistry Practice Questions
IB (International Baccalaureate) · IB Chemistry HL · 145 free MCQs with instant results and detailed explanations.
145
Total
38
Easy
76
Medium
31
Hard
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Sample Questions from Organic Chemistry
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Q1
Easy
Which of the following statements correctly describes an alkane?
A.
Alkanes contain only single bonds between carbon atoms.
B.
Alkanes can have double bonds and triple bonds.
C.
Alkanes are saturated hydrocarbons with at least one double bond.
D.
Alkanes have the general formula CnH2n-2.
Show Answer & Explanation
Correct Answer: A
Alkanes are indeed saturated hydrocarbons that contain only single bonds between carbon atoms, making option A correct.
Q2
Easy
What is the primary product formed when ethene undergoes hydrogenation?
A.
Ethane
B.
Ethanol
C.
Ethyl bromide
D.
Butane
Show Answer & Explanation
Correct Answer: A
The primary product of hydrogenation of ethene is ethane, where hydrogen adds across the double bond, thus making option A correct.
Q3
Easy
Which functional group characterizes alcohols in organic chemistry?
A.
-OH
B.
-COOH
C.
-NH2
D.
-CHO
Show Answer & Explanation
Correct Answer: A
The functional group that characterizes alcohols is the hydroxyl group (-OH), making option A the correct choice.
Q4
Medium
What is the main product when propanoic acid reacts with sodium bicarbonate?
A.
Sodium propanoate
B.
Propane
C.
Sodium acetate
D.
Carbon dioxide
Show Answer & Explanation
Correct Answer: A
When propanoic acid reacts with sodium bicarbonate, it forms sodium propanoate and carbonic acid, which decomposes to water and carbon dioxide. The predominant product is sodium propanoate.
Q5
Medium
Which of the following statements about alkanes is TRUE?
A.
Alkanes are unsaturated hydrocarbons.
B.
Alkanes generally have higher boiling points than alkenes.
C.
Alkanes undergo addition reactions easily.
D.
Alkanes are stable and do not readily react with strong oxidizing agents.
Show Answer & Explanation
Correct Answer: D
Alkanes are saturated hydrocarbons and are relatively stable, making them less reactive towards strong oxidizing agents compared to other organic compounds. They do not readily undergo addition reactions.
Q6
Medium
What mechanism primarily describes the reaction of halogenoalkanes with nucleophiles?
A.
Electrophilic addition
B.
Nucleophilic substitution
C.
Elimination
D.
Radical substitution
Show Answer & Explanation
Correct Answer: B
The reaction of halogenoalkanes with nucleophiles is primarily described by nucleophilic substitution mechanisms, where the nucleophile replaces the halogen atom in the halogenoalkane.
Q7
Medium
What is the expected product when cyclohexene undergoes hydrogenation?
A.
Cyclohexane
B.
Cyclohexanol
C.
Hexane
D.
Cyclohexanone
Show Answer & Explanation
Correct Answer: A
When cyclohexene undergoes hydrogenation, it reacts with hydrogen gas in the presence of a catalyst to form cyclohexane, a saturated hydrocarbon. The double bond in cyclohexene is converted to a single bond during this reaction.
Q8
Hard
Which of the following compounds will undergo nucleophilic substitution the fastest?
A.
2-bromopropane
B.
1-bromobutane
C.
2-chlorobutane
D.
1-chlorobutane
Show Answer & Explanation
Correct Answer: A
2-bromopropane is a secondary alkyl halide, which is more reactive in nucleophilic substitution reactions compared to primary compounds like 1-bromobutane due to steric hindrance. The presence of a bromine atom also facilitates the reaction due to its better leaving group ability compared to chlorine.
Q9
Hard
When propan-1-ol undergoes oxidation by potassium dichromate, which of the following products is predominantly formed?
A.
Propanal
B.
Propanoic acid
C.
2-propanol
D.
Ethylene
Show Answer & Explanation
Correct Answer: B
Propan-1-ol is a primary alcohol that, when oxidized by potassium dichromate, is converted to propanoic acid as the major product due to a two-step oxidation process. The initial conversion is to propanal, but further oxidation leads to propanoic acid.
Q10
Hard
Which of the following compounds has the highest boiling point due to hydrogen bonding?
A.
Ethanol (C2H5OH)
B.
Hexane (C6H14)
C.
Acetone (C3H6O)
D.
Benzene (C6H6)
Show Answer & Explanation
Correct Answer: A
Ethanol exhibits hydrogen bonding due to the presence of an -OH group, resulting in stronger intermolecular forces compared to hexane, acetone, and benzene which do not have hydrogen bonding.
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Organic Chemistry — IB (International Baccalaureate) IB Chemistry HL Practice Questions Online
This page contains 145 practice MCQs for the chapter Organic Chemistry in IB (International Baccalaureate) IB Chemistry HL. The questions are organized by difficulty — 38 easy, 76 medium, 31 hard — so you can choose the right level for your preparation.
Every question includes a detailed explanation to help you understand the concept, not just memorize answers. Take a timed quiz to simulate exam conditions, or practice at your own pace with no time limit.