Detection of the following Functional Groups: Hydroxyl, Carbonyl Carboxyl, and Amino Groups in Organic Compounds NEET Questions

Organic Chemistry - Principles of Practical Chemistry

Detection of the following Functional Groups: Hydroxyl, Carbonyl Carboxyl, and Amino Groups in Organic Compounds MCQ Questions


13.
The ester (sweet fruity smell) test for alcohols involves heating the alcohol with:
A.
Phthalic anhydride + dil. NaOH
B.
Carboxylic acid + concentrated H2SO4
C.
NaOH + I2
D.
Anhydrous ZnCl2 + HCl
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ANSWER :
B. Carboxylic acid + concentrated H2SO4
14.
In the ester test, concentrated H2SO4 acts as:
A.
Dehydrating agent / acid catalyst
B.
Reagent that supplies –OH
C.
Oxidising agent
D.
Reducing agent
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ANSWER :
A. Dehydrating agent / acid catalyst
15.
Why is the ceric ammonium nitrate test for alcohols carried out using a non-aqueous solvent like dioxane when the alcohol is high-molecular-weight?
A.
Dioxane increases sensitivity by lowering pH
B.
To prevent oxidation of the alcohol
C.
High alcohols are insoluble in water; dioxane gives a homogeneous medium
D.
To suppress the reaction of phenols
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ANSWER :
C. High alcohols are insoluble in water; dioxane gives a homogeneous medium
16.
Which alcohol gives the fastest reaction with Lucas reagent at room temperature?
A.
Isobutyl alcohol
B.
n-Butyl alcohol
C.
sec-Butyl alcohol
D.
tert-Butyl alcohol
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ANSWER :
D. tert-Butyl alcohol
17.
Sodium metal test cannot distinguish between an alcohol and a carboxylic acid because:
A.
Carboxylic acids do not react with Na
B.
Both give the same coloured complex
C.
Both contain an active –OH and liberate H2 with Na
D.
Alcohols give CO2 with Na
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ANSWER :
C. Both contain an active –OH and liberate H2 with Na
18.
Why does the red colour with ceric ammonium nitrate fade on standing or with excess reagent?
A.
Ce(IV) oxidises the alcohol to a carbonyl compound and is itself reduced to colourless Ce(III)
B.
The alcohol evaporates
C.
The complex decomposes to give a colourless precipitate of cerium hydroxide
D.
Ammonium nitrate decomposes
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ANSWER :
A. Ce(IV) oxidises the alcohol to a carbonyl compound and is itself reduced to colourless Ce(III)