Question

Which of the following does not exihibit the phenomena of mutarotation?

A. $$\left( + \right)$$  Sucrose  
B. $$\left( + \right)$$  Lactose
C. $$\left( + \right)$$  Maltose
D. $$\left( - \right)$$  Fructose
Answer :   $$\left( + \right)$$  Sucrose
Solution :
Key Idea Reducing sugars that exist in hemiacetal and hemiketal forms, exhibit the phenomenon of mutarotation in aqueous solution. During mutarotation, the ring open upto give the open chain form which then reclose either in the inverted position or in the original position giving an equilibrium mixture of two anomers with a small amount of open chain form. Thus, all reducing monosaccharides and disaccharides undergo mutarotation in aqueous solution.
Among the given carbohydrates, only sucrose is a non-reducing sugar as in it the hemiacetal and hemiketal groups of glucose and fructose are linked together through $$O$$ - atom and thus, not free. Due to the absence of free hemiacetal or hemiketal group, sucrose does not exhibit mutarotation.

Releted MCQ Question on
Organic Chemistry >> Biomolecules

Releted Question 1

The pair of compounds in which both the compounds give positive test with Tollen’s reagent is

A. Glucose and Sucrose
B. Fructose and Sucrose
C. Acetophenone and Hexanal
D. Glucose and Fructose
Releted Question 2

The two forms of $$D - $$ glucopyranose obtained from the solution of $$D - $$ glucose are called

A. Isomers
B. Anomers
C. Epimers
D. Enantiomers
Releted Question 3

Cellulose upon acetylation with excess acetic anhydride/ $${H_2}S{O_4}$$  (catalytic) gives cellulose triacetate whose structure is

A. Biomolecules mcq option image
B. Biomolecules mcq option image
C. Biomolecules mcq option image
D. Biomolecules mcq option image
Releted Question 4

The following carbohydrate is
Biomolecules mcq question image

A. a ketohexose
B. an aldohexose
C. an $$\alpha $$ - furanose
D. an $$\alpha $$ - pyranose

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Biomolecules


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