Alkynes(Acidic Character: Addition of Hydrogen,...) NEET Questions

Organic Chemistry - Hydrocarbons

Alkynes(Acidic Character: Addition of Hydrogen,...) MCQ Questions


7.
What is the product when 1-butyne reacts with NaNH2 in liquid ammonia?
A.
CH3-CH2-C≡CH + NaNH3
B.
CH3-CH2-C≡C⁻Na⁺
C.
CH3-CH2-CH=CH2
D.
CH3-CH2-CH2-CH3
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ANSWER :
B. CH3-CH2-C≡C⁻Na⁺
8.
Which reagent is used to distinguish between but-1-yne and but-2-yne?
A.
Concentrated H2SO4
B.
Bromine water
C.
Baeyer's reagent (cold dilute KMnO4)
D.
Ammoniacal AgNO3 / Ammoniacal Cu2Cl2
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ANSWER :
D. Ammoniacal AgNO3 / Ammoniacal Cu2Cl2
9.
Why is ethyne more acidic than ethene?
A.
sp orbitals have higher electronegativity than sp² orbitals due to greater s-character
B.
Ethyne has fewer hydrogen atoms
C.
Triple bond is stronger than double bond
D.
π-electrons in ethyne are more delocalized
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ANSWER :
A. sp orbitals have higher electronegativity than sp² orbitals due to greater s-character
10.
When propyne reacts with sodium in liquid ammonia, the major product is:
A.
Propene and NaH
B.
Disodium propynide
C.
Sodium propynide (CH3-C≡C⁻Na⁺)
D.
Propane and NaNH2
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ANSWER :
C. Sodium propynide (CH3-C≡C⁻Na⁺)
11.
Disodium acetylide (Na⁺C⁻≡C⁻Na⁺) is formed when ethyne reacts with:
A.
Sodium chloride
B.
Sodium bicarbonate
C.
Sodium hydroxide
D.
Excess sodium metal
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ANSWER :
D. Excess sodium metal
12.
The acidic hydrogen in alkynes is best explained by:
A.
Steric effects of triple bond
B.
Greater electronegativity of sp-hybridized carbon
C.
Resonance stabilization of the alkyne
D.
Hyperconjugation effect
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ANSWER :
B. Greater electronegativity of sp-hybridized carbon