Final answer:
The statement about carbocations that is not true is that they are formed by homolytic bond fission. They are actually formed by heterolytic bond fission, making option 3 the correct answer.
Step-by-step explanation:
To address the question regarding carbocations, we will look at which statement is not true for a carbocation:
- A carbocation is electrophile.
- A carbocation is diamagnetic in character.
- It is formed by homolytic bond fission.
- It reacts with nucleophiles.
A carbocation is indeed an electrophile, which means it seeks out electrons to form a complete octet. This makes the first statement true. Regarding the second statement, carbocations are indeed diamagnetic, as they do not possess any unpaired electrons. As for the fourth statement, carbocations are known to react with nucleophiles; this happens because the positively charged carbon atom in a carbocation is an enticing target for nucleophiles looking to donate an electron pair.
The statement that is not true for carbocations is the third one: "It is formed by homolytic bond fission." Instead, carbocations are typically formed by heterolytic bond fission, where one atom in a bond takes both electrons, leaving the other atom as a positively charged carbocation.
Therefore, the correct option is:3. It is formed by homolytic bond fission.