Question

The number of stereocenters present in linear and cyclic structures of glucose are respectively:
(A) 4 and 5
(B) 5 and 5
(C) 4 and 4
(D) 5 and 4

Answer 1

Hint: Stereo Centre is nothing but a chiral center. A carbon which is attached to three or more different substituents is called a chiral center. If a molecule is optically active, that molecule should contain at least one chiral center in it.

Complete step by step answer:
* In the question it is given to find the number of stereocenters present in linear and cyclic structures of glucose.
* Sterocenter is nothing but the chiral center. If a carbon atom is attached to four different atoms are different groups then it is called stereocenter or chiral center.
* Chiral centers are optically active in nature.
* Linear structure and cyclic structures of glucose are as follows.

* The chiral centers are marked with red color stars.
* The number of chiral or stereo centers in linear structure of glucose are 4.
* The number of chiral or stereo centers in cyclic structure of glucose are 5.
* Therefore the number of chiral or stereo centers in linear structure and cyclic structures of glucose are 4. And 5 respectively.

So, the correct answer is A.

Additional information:
There is a reason behind one extra chiral carbon in cyclic glucose when compared to linear glucose is, after cyclisation of linear glucose one of the achiral carbon in linear structure is going to convert into chiral carbon.

Note: Linear structure of molecules is for our understanding purpose only, originally glucose exists in cyclic structures only with five chiral or stereo centers. The number of optically active isomers is also high for cyclic glucose structure when compared to linear structure of glucose.