Isomerism

Isomerism

Q. 1 Identify the Carbohydrate marked as A and B in the Diagram ?

 A A is Fructose and B is Glucose

 B

A is glucose and B is Fructose

 C

Both A and B is Glucose but Optical Isomers

 D

Both A and B is Fructose but Opitcal Isomers

Q. 1

Identify the Carbohydrate marked as A and B in the Diagram ?

 A

A is Fructose and B is Glucose

 B

A is glucose and B is Fructose

 C

Both A and B is Glucose but Optical Isomers

 D

Both A and B is Fructose but Opitcal Isomers

Ans. B

Explanation:


Q. 2

Identify the isomerism shown in the diagram ?

 A

Structural Isomerism 

 B

Stereoisomerism

 C

Opical Isomerism

 D

Anomerism

Ans. B

Explanation:

stereoisomers are isomeric molecules that have the same molecular formula and sequence of bonded atoms (constitution), but differ in the three-dimensional orientations of their atoms in space.


Q. 3

Alpha D Glucose and Beta D Glucose are examples of:

 A

Epimers

 B

Anomers 

 C

Optical Isomers 

 D

Stereoisomers

Ans. B

Explanation:

When D glucose is crystallized at room temperature, and a fresh solution is prepared, its specific rotation of polarized light is +1120; but after 12-18 hours it changes to +52.5o. If initial crystallization is taking place at 980C and then solubilized, the specific rotation is found to be +19o, which also changes to +52.5o within a few hours. This change in rotation with time is called mutarotation.

This is explained by the fact that D-glucose has two anomers, alpha and beta varieties. These anomers are produced by the spatial configuration with reference to the first carbon atom in aldoses and second carbon atom in ketoses.
Hence, these carbon atoms are known as anomeric carbon atoms.


Q. 4

The conversion of an optically pure isomer into a mixture of equal amounts of both dextro and levo forms is called as-

 A

Polymerization

 B

Stereoisomerism

 C

Racemization

 D

Fractionation

Ans. C

Explanation:

 Racemic Mixture – Equimolar mixture of optical isomers which has no net reaction of plane-polarized light.

An Equimolar mixture of optical isomers has no net rotation.



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