(a) How many sigma and pi bonds are there in the following:
CH2 = CH - CH2 - C = CH
(b) Which type of hybrid orbitals are used by the second carbon atom in the following molecule:
\(\overset{5}{CH}\equiv\overset{4}{C}-\overset{3}{CH_2}-\overset{2}{CH}-\overset{1}{CH_2}\)