QJEEAdv08Ch8133: JEE Advanced 2008 Chemistry - Class 11 JEEAdv08Ch8133 Solution: The correct stability order for the following species is :

Stability of the following species depends upon the no. of $$\alpha$$ hydrogen which can undergoes hyperconjugation as well as resonance. Higher the no. of $$\alpha$$ hydrogen, higher will be the stability of the carbocation.

Stabilizes by resonance and have six $$\alpha$$-hydrogen atoms (hyperconjugation).

Stabilizes by resonance and have three $$\alpha$$-hydrogen atoms.

It have five $$\alpha$$-hydrogen atoms.

It have only two $$\alpha$$-hydrogen atoms.

$$\therefore$$ (I) > (III) > (II) > (IV)