The most stable cation shown in the image is structure IV. This is because it is a tertiary carbocation.
The most stable cation shown in the image is structure IV. This is because it is a tertiary carbocation.
Tertiary carbocations are more stable than secondary and primary carbocations because they have more alkyl groups attached to the positively charged carbon atom.
The more alkyl groups attached, the better they can delocalize the positive charge, which makes the cation more stable.
Structures I and II are both secondary carbocations, and structure III is a primary carbocation. Therefore, structure IV is the most stable cation.
Here is the of order of stability of carbocations:
Tertiary carbocations > secondary carbocations > primary carbocations
The probable structures is attached below.