EXERCISE

$2\mathrm{.}18(1)$ Write the resonance structures of the following ions. $(2)$ State which structure $($if any$)$ contributes more to the actual structure. Which ones have the same energy? $[($b$)$ too Use the Kekul$$ formula$).$

$($a$)CH,CH-CHC{C}^{+}HCH,$

$($b$)$

$($c$)$

$($d$)$ : $CH,CN$ :