Arrange the following carbocations in decreasing order of their stability: (i) (ii) (iii) (iv)

Step-by-step solution

The given species are all aromatic carbocations. Their stability depends on the extent of delocalization, substituent effects, and ring strain. (i) Tricyclopropylcyclopropenyl cation: It is an aromatic ( 2 electrons) system. The positive charge is exceptionally stabilized by the strong -conjugation (dancing resonance) of the three cyclopropyl groups. This makes it the most stable carbocation among the given options ( pK_ R ⁺ 10.0 ). (iii) Tropylium cation: It is a seven-membered aromatic ring with 6 electrons. It h