Question

The decreasing order of stability of alkyl carbocation is:

Answer 1

Hint: As we know that carbocation is a group of atoms in which a carbon atom is positively charged. Carbocation is an electron deficient species.

Complete answer:
As tertiary carbocation contains three alkyl groups, so they have three methyl groups to distribute its positive charge than primary and secondary carbocation because they both contain one and two alkyl groups respectively. Three H-atoms are attached in the methyl group but adjacent hydrogen does not stabilize carbocation. So, the decreasing order of stability of carbocation is as follows:
Tertiary > secondary > primary > methyl



Hence, the correct answer is A.

Additional Information:
In carbocation, the hybridization of carbon is and its shape is trigonal planar. The empty p orbital indicates that it has an electron-deficient nature. The carbon has 6 electrons in its valence shell. Carbocation is formed by two ways they are cleavage of bonds of carbon and electrophilic addition. The cleavage of the carbon bond and the atoms attached to it takes away the shared electrons from the leaving group. And it makes the carbon atom deficient as an electron. As a result, a positive charge is formed which is known as carbocation. An electrophile attacks on an unsaturated point (that is double or triple bond) in electrophilic addition, this results in the cleavage of the pi bond which results in the formation of a carbocation.

Note:
Students might confuse among primary, secondary and tertiary alkyl groups. Primary carbon is bonded to one other carbon while tertiary and secondary are bonded to three and two carbon respectively.