Q. What is the bond angle around the carbon atoms in an alkyne?
A.
120 degrees
B.
180 degrees
C.
109.5 degrees
D.
90 degrees
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Solution
The bond angle around the carbon atoms in an alkyne is approximately 180 degrees due to linear geometry.
Correct Answer:
B
— 180 degrees
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Q. What is the general formula for alkynes?
A.
C_nH_(2n+2)
B.
C_nH_(2n)
C.
C_nH_(2n-2)
D.
C_nH_(2n-1)
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Solution
The general formula for alkynes is C_nH_(2n-2), where n is the number of carbon atoms.
Correct Answer:
C
— C_nH_(2n-2)
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Q. What is the hybridization of the carbon atoms in an alkyne?
A.
sp
B.
sp2
C.
sp3
D.
dsp3
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Solution
In alkynes, the carbon atoms involved in the triple bond are sp hybridized.
Correct Answer:
A
— sp
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Q. What is the hybridization of the carbon atoms in ethyne (C2H2)?
A.
sp
B.
sp2
C.
sp3
D.
dsp3
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Solution
In ethyne, the carbon atoms are sp hybridized due to the presence of a triple bond.
Correct Answer:
A
— sp
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Q. What is the IUPAC name of the compound CH≡C-CH2-CH3?
A.
1-butyne
B.
2-butyne
C.
1-pentyne
D.
3-pentyne
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Solution
The IUPAC name of CH≡C-CH2-CH3 is 1-butyne.
Correct Answer:
A
— 1-butyne
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Q. What is the IUPAC name of the compound with the formula C4H6?
A.
1-butyne
B.
2-butyne
C.
Cyclobutene
D.
Butadiene
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Solution
The compound C4H6 is named 2-butyne according to IUPAC nomenclature.
Correct Answer:
B
— 2-butyne
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Q. What is the main feature of terminal alkynes?
A.
They have a triple bond in the middle
B.
They can form carbanions
C.
They are less acidic than alkenes
D.
They cannot undergo substitution reactions
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Solution
Terminal alkynes can form carbanions due to the acidity of the hydrogen atom attached to the sp-hybridized carbon.
Correct Answer:
B
— They can form carbanions
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Q. What is the main feature that distinguishes alkynes from alkenes?
A.
Presence of double bonds
B.
Presence of triple bonds
C.
Saturation
D.
Molecular weight
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Solution
Alkynes are distinguished from alkenes by the presence of triple bonds.
Correct Answer:
B
— Presence of triple bonds
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Q. What is the main product when 1-butyne is treated with HBr?
A.
1-bromobutane
B.
2-bromobutane
C.
1,2-dibromobutane
D.
No reaction
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Solution
When 1-butyne reacts with HBr, the main product is 2-bromobutane due to Markovnikov's rule.
Correct Answer:
B
— 2-bromobutane
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Q. What is the main product when 2-butyne is treated with excess H2 in the presence of a catalyst?
A.
1-butyne
B.
Butane
C.
2-butyne
D.
Ethyne
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Solution
The main product is butane, as 2-butyne is fully hydrogenated to form butane.
Correct Answer:
B
— Butane
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Q. What is the main product when 2-butyne undergoes hydroboration-oxidation?
A.
Butanol
B.
Butanal
C.
Butyric acid
D.
Butene
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Solution
The main product is Butanol when 2-butyne undergoes hydroboration-oxidation.
Correct Answer:
A
— Butanol
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Q. What is the major product of the reaction of 2-butyne with H2 in the presence of a catalyst?
A.
1-butyne
B.
butane
C.
2-butyne
D.
3-butyne
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Solution
The major product of hydrogenation of 2-butyne is butane.
Correct Answer:
B
— butane
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Q. What is the product of the complete combustion of an alkyne?
A.
CO2 and H2O
B.
CO and H2O
C.
C and H2O
D.
C2H4
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Solution
The complete combustion of an alkyne produces carbon dioxide (CO2) and water (H2O).
Correct Answer:
A
— CO2 and H2O
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Q. What is the product of the complete hydrogenation of 2-butyne?
A.
1-butyne
B.
2-butyne
C.
butane
D.
butyne
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Solution
The complete hydrogenation of 2-butyne results in butane.
Correct Answer:
C
— butane
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Q. What is the product of the reaction between 1-butyne and HBr?
A.
1-bromobutane
B.
2-bromobutane
C.
butane
D.
butyne
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Solution
The reaction of 1-butyne with HBr leads to the formation of 2-bromobutane due to Markovnikov's rule.
Correct Answer:
B
— 2-bromobutane
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Q. What is the product of the reaction of 1-butyne with HBr?
A.
1-bromobutane
B.
2-bromobutane
C.
Butane
D.
Butyne
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Solution
The reaction of 1-butyne with HBr leads to the formation of 2-bromobutane due to Markovnikov's rule.
Correct Answer:
B
— 2-bromobutane
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Q. What type of hybridization is present in alkynes?
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Solution
Alkynes have sp hybridization due to the presence of a triple bond.
Correct Answer:
A
— sp
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Q. What type of hybridization occurs in the carbon atoms of alkynes?
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Solution
In alkynes, the carbon atoms are sp hybridized.
Correct Answer:
A
— sp
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Q. What type of isomerism is shown by 1-butyne and 2-butyne?
A.
Structural isomerism
B.
Geometric isomerism
C.
Optical isomerism
D.
Conformational isomerism
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Solution
1-butyne and 2-butyne are structural isomers as they differ in the position of the triple bond.
Correct Answer:
A
— Structural isomerism
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Q. Which of the following alkynes is symmetrical?
A.
1-butyne
B.
2-butyne
C.
1-pentyne
D.
3-pentyne
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Solution
2-butyne is a symmetrical alkyne.
Correct Answer:
B
— 2-butyne
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Q. Which of the following alkynes is the most acidic?
A.
Ethylene
B.
Propyne
C.
Butyne
D.
Acetylene
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Solution
Acetylene (ethyne) is the most acidic among the given alkynes due to the sp hybridization of carbon.
Correct Answer:
D
— Acetylene
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Q. Which of the following alkynes is the most stable?
A.
1-butyne
B.
2-butyne
C.
1-pentyne
D.
3-pentyne
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Solution
2-butyne is more stable than 1-butyne due to steric hindrance and hyperconjugation.
Correct Answer:
B
— 2-butyne
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Q. Which of the following alkynes is the simplest?
A.
1-butyne
B.
2-butyne
C.
Ethyne
D.
Propyne
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Solution
Ethyne (C2H2) is the simplest alkyne.
Correct Answer:
C
— Ethyne
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Q. Which of the following compounds is an alkyne?
A.
C2H4
B.
C3H6
C.
C4H8
D.
C5H8
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Solution
C5H8 is an alkyne, as it follows the general formula C_nH_(2n-2).
Correct Answer:
D
— C5H8
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Q. Which of the following compounds is an aromatic alkyne?
A.
Phenylacetylene
B.
Propyne
C.
Ethyne
D.
1-butyne
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Solution
Phenylacetylene is an aromatic alkyne as it contains a phenyl group attached to a triple bond.
Correct Answer:
A
— Phenylacetylene
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Q. Which of the following compounds is the most acidic?
A.
Ethylene
B.
Propene
C.
Propyne
D.
Butyne
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Solution
Propyne is the most acidic due to the sp hybridization of the carbon atom involved in the triple bond.
Correct Answer:
C
— Propyne
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Q. Which of the following is a characteristic property of alkynes?
A.
Higher boiling points than alkenes
B.
Lower reactivity than alkenes
C.
Inability to undergo addition reactions
D.
Higher density than alkanes
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Solution
Alkynes generally have higher boiling points than alkenes due to stronger intermolecular forces.
Correct Answer:
A
— Higher boiling points than alkenes
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Q. Which of the following is a terminal alkyne?
A.
1-butyne
B.
2-butyne
C.
1-pentyne
D.
3-pentyne
Show solution
Solution
1-butyne is a terminal alkyne because it has a triple bond at the end of the carbon chain.
Correct Answer:
A
— 1-butyne
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Q. Which of the following is the correct reaction for the hydrogenation of 1-butyne?
A.
C4H6 + H2 → C4H10
B.
C4H6 + H2 → C4H8
C.
C4H6 + H2 → C4H12
D.
C4H6 + H2 → C4H4
Show solution
Solution
1-butyne (C4H6) reacts with hydrogen (H2) to form butene (C4H8) under catalytic conditions.
Correct Answer:
B
— C4H6 + H2 → C4H8
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Q. Which of the following is the correct structure for 2-butyne?
A.
CH3-C≡C-CH3
B.
CH3-CH≡C-CH3
C.
CH3-C=C-CH3
D.
C≡C-CH2-CH3
Show solution
Solution
2-butyne has the structure CH3-CH≡C-CH3, with the triple bond between the second and third carbon.
Correct Answer:
B
— CH3-CH≡C-CH3
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Showing 1 to 30 of 50 (2 Pages)
Alkynes MCQ & Objective Questions
Alkynes are a crucial topic in organic chemistry that students must master for their exams. Understanding alkynes not only enhances your conceptual clarity but also boosts your confidence in tackling MCQs and objective questions. Practicing these important questions can significantly improve your exam preparation and help you score better in school and competitive exams.
What You Will Practise Here
Definition and general formula of alkynes
Structure and bonding in alkynes
Reactions of alkynes, including addition and substitution reactions
Physical properties and uses of alkynes
Isomerism in alkynes
Preparation methods for alkynes
Key differences between alkenes and alkynes
Exam Relevance
Alkynes are frequently featured in various examinations, including CBSE, State Boards, NEET, and JEE. Students can expect questions related to the properties, reactions, and applications of alkynes. Common question patterns include multiple-choice questions that test your understanding of the structure and reactivity of alkynes, as well as their comparison with other hydrocarbons. Mastering this topic can give you an edge in both theoretical and practical assessments.
Common Mistakes Students Make
Confusing the general formula of alkynes with that of alkenes.
Overlooking the significance of hybridization in determining the properties of alkynes.
Misunderstanding the types of reactions that alkynes can undergo.
Failing to recognize isomerism in alkynes and its implications.
FAQs
Question: What is the general formula for alkynes?Answer: The general formula for alkynes is CnH2n-2.
Question: How do alkynes differ from alkenes?Answer: Alkynes contain a triple bond between carbon atoms, while alkenes have a double bond.
Now is the perfect time to enhance your understanding of alkynes. Dive into our practice MCQs and test your knowledge to ensure you are well-prepared for your upcoming exams. Remember, consistent practice is key to success!
