The state of hybridization of C2 , C3 , C5 and C6 of hydrocarbon :

2nd carbon around 2 σ bonds so Sp hybridization.3rd carbon around 4 σ bonds so Sp3 hybridization5 th carbon around 3 σ bonds so Sp2 hybridization.6th carbon around 4 σ bonds so Sp3 hybridization