Organic Chemistry Practice Questions
IGCSE (Cambridge) · IGCSE Chemistry · 138 free MCQs with instant results and detailed explanations.
138
Total
34
Easy
73
Medium
31
Hard
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Sample Questions from Organic Chemistry
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Q1
Easy
Which of the following is the general formula for alkanes?
A.
CnH2n+2
B.
CnH2n
C.
CnH2n-2
D.
CnH2n+1OH
Show Answer & Explanation
Correct Answer: A
The general formula for alkanes is CnH2n+2, where 'n' is the number of carbon atoms. This formula indicates that for every carbon atom, there are two hydrogen atoms plus two additional hydrogen atoms in saturated hydrocarbons.
Q2
Easy
What is the primary functional group found in alcohols?
A.
Carboxyl group (-COOH)
B.
Hydroxyl group (-OH)
C.
Carbonyl group (C=O)
D.
Amine group (-NH2)
Show Answer & Explanation
Correct Answer: B
The primary functional group in alcohols is the hydroxyl group (-OH). This group characterizes alcohols and is responsible for their chemical properties, such as solubility in water.
Q3
Easy
Which process is used to convert an alkene into an alkane?
A.
Hydrogenation
B.
Halogenation
C.
Hydrolysis
D.
Oxidation
Show Answer & Explanation
Correct Answer: A
Hydrogenation is the process where hydrogen is added to an alkene, converting it into an alkane. This reaction typically occurs in the presence of a catalyst, resulting in the saturation of the carbon double bond.
Q4
Medium
Which of the following compounds is an example of an alkene?
A.
C2H4
B.
C3H8
C.
C4H10
D.
C5H12
Show Answer & Explanation
Correct Answer: A
C2H4 is an alkene because it contains a double bond between carbon atoms. Alkenes are characterized by at least one carbon-carbon double bond.
Q5
Medium
What is the main product when ethene reacts with chlorine gas?
A.
Chloroethane
B.
1,2-Dichloroethane
C.
Ethane
D.
Ethyl chloride
Show Answer & Explanation
Correct Answer: B
When ethene reacts with chlorine gas, it undergoes electrophilic addition, resulting in 1,2-Dichloroethane, where two chlorine atoms are added across the double bond.
Q6
Medium
What type of reaction occurs when a carboxylic acid reacts with an alcohol?
A.
Dehydration synthesis
B.
Esterification
C.
Hydrolysis
D.
Combustion
Show Answer & Explanation
Correct Answer: B
The reaction between a carboxylic acid and an alcohol is known as esterification, producing an ester and water, which is a key reaction in organic chemistry.
Q7
Medium
Which of the following statements about hydrocarbons is true?
A.
All hydrocarbons are soluble in water.
B.
Alkanes are unsaturated hydrocarbons.
C.
Alkenes contain double bonds.
D.
All hydrocarbons are gaseous at room temperature.
Show Answer & Explanation
Correct Answer: C
Alkenes are indeed hydrocarbons that contain at least one double bond, distinguishing them from alkanes, which are saturated hydrocarbons with only single bonds.
Q8
Hard
Which of the following statements about alkenes is NOT true?
A.
Alkenes can undergo addition reactions.
B.
Alkenes have a double bond between carbon atoms.
C.
Alkenes are saturated hydrocarbons.
D.
Alkenes can form polymers through addition reactions.
Show Answer & Explanation
Correct Answer: C
Alkenes are unsaturated hydrocarbons because they contain a double bond, which makes them capable of undergoing addition reactions. Saturated hydrocarbons, like alkanes, only have single bonds.
Q9
Hard
What is the product of the complete combustion of ethylene (C2H4)?
A.
Carbon dioxide and water
B.
Carbon monoxide and water
C.
Carbon and hydrogen
D.
Ethane and oxygen
Show Answer & Explanation
Correct Answer: A
The complete combustion of ethylene (C2H4) involves its reaction with oxygen to produce carbon dioxide and water, releasing energy in the process. This is a characteristic reaction for alkenes during combustion.
Q10
Hard
Which of the following compounds would exhibit optical isomerism?
A.
2-butanol
B.
1-butyne
C.
Butanoic acid
D.
Cyclohexane
Show Answer & Explanation
Correct Answer: A
2-butanol has a chiral carbon atom, which allows it to exist in two non-superimposable mirror images (enantiomers), thus exhibiting optical isomerism. The other compounds do not have chiral centers.
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Organic Chemistry — IGCSE (Cambridge) IGCSE Chemistry Practice Questions Online
This page contains 138 practice MCQs for the chapter Organic Chemistry in IGCSE (Cambridge) IGCSE Chemistry. The questions are organized by difficulty — 34 easy, 73 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.