Question

How many structures of X is possible?

A) 4
B) 5
C) 6
D) 3

Answer 1

Alcohol attacks on acid so, the water molecule removes from the reactant forming a carbocation. Then the proton removes from nearby carbon to form an alkene. The alkene can show geometrical isomerism.

Complete answer:
The lone pair of electrons of the hydroxyl group of the reactant attacks on the acid and gets protonated. Then the water molecule removes forming a carbocation.
The formation of the carbocation is shown as follows:

After the formation of the carbocation, proton from nearby carbon removes to form an alkene.
The hydrogen can remove from terminal carbon or the secondary carbon.so, two types of an alkene will be formed.
The formation of alkene is shown as follows:

The 1-butane can exist only in one form but the 2-butane can exist in two forms which are known as isomers.
The two isomers of 2-butane are shown as follows:

So, total three structures of is possible one is 1-butane and isomers of 2-butane.

Therefore, option (D) 3 is correct.

Note: The less substituted alkene that is 1-butane is known as Hoffmann product and the more substituted alkene that is 2-butane is known as saytzeff product. The compounds having the same chemical formula and different arrangements of atoms are known as isomerism. Geometrical isomerism is shown by the compounds that have a different arrangement of atoms around the unsaturated bond.