Transition state 2 is structurally most likely as :

Khowing something about the structure of a transition state is important when you are trying to predict the products of a reaction. The structure of the transition state lies
between the structure of the reactants and the structure of the products. But what do we mean by "between"? Does the structure of the transition state lie exactly halfway between  the structures of the reactants and products (as in II, below), or does it resemble the reactants more closely than it resembles the products (as in I), or is it more like the products than the reactants (as in III)?

According to the Hammond postulate, the transition state will be more similar in structure to the species that it is more similar to in energy. In the case of an exergonic reaction, the transition state is more similar in energy to the reactant than to the product. (curve I). Therefore, the structure of the transition state will more closely resemble the structure of the reactant than that of the transition state will more closely resemble the structure of the reactant than that of the product. In an endergonic reaction (curve III), the transition state is more similar in energy to the product, so the structure of the transition state will more closely resemble the structure of the product. Only when the reactant and the product have identical energies (curve II) would we expect the structure of the transition state to be halfway between the structures of the reactant and the product.
Now we can understand why the tert-butyl cation is formed faster than the isobutyl cation when 2-methylpropene reacts with HCl. Of the two possible products, the tert-butyl
cation (a tertiary carbocation) is more stable than the isobutyl cation (a primary carbocation). Because formation of a carbocation is an endergonic reaction, the structure
of the transition state will resemble the structure of the carbocation product. This means that the uansition state will have a significant amount of positive charge on a carbon. The same factors that stabilize the positively charged product will stabilize the partially positively charged transition state. Therefore, the transition state leading to the ten-buryl

cation is more stable than the transition state leading to the isobutyl cation, so the tert-butyl cation will be formed faster. It is important to keep in mind that the amount of
positive charge in the transition state is not as great as the amount of positive charge in the transition state is not as great as the amount of positive charge in the carbocation product, so the difference in the stabilities of the two transition states is not as great as the difference in the stabilities of the two carbocation products.