(i)

C–1 is sp2 hybridised.
C–2 is sp hybridised.
(ii)

C–1 is sp3 hybridised.
C–2 is sp2 hybridised.
C–3 is sp2 hybridised.
(iii)

C–1 and C–3 are sp3 hybridised.
C–2 is sp2 hybridised.
(iv)

C–1 is sp2 hybridised.
C–2 is sp2 hybridised.
C–3 is sp hybridised.
(v) C6H6
All the 6 carbon atoms in benzene are sp2 hybridised.