The most carbocations, carbanions, free radicals and radical cations are reactive carbon intermediates.

Their hybrid orbitals respectively are:

Which of the following structure is aromatic?

How many hyperconjugative structures are possible in the following carbocation?

Which of the following compound(s) is/are an aromatic compounds?

$\left(\mathrm{i}\right)$ 

$\left(\mathrm{ii}\right)$ 

$\left(\mathrm{iii}\right)$ 

$\left(\mathrm{iv}\right)$