Answer
a) alkene
b) alkyne
c) alkane
d) alkyne
Work Step by Step
The general formula of hydrocarbons is :
Alkane - $C_nH_{2n+2}$
Alkene - $C_nH_{2n}$
Alkyne - $C_nH_{2n-2}$
a) Fits in the formula of alkene (n = 8)
b) Fits in the formula of alkyne (n = 4)
c) Fits in the formula of alkane (n=7)
d) Fits in the formula of alkyne (n = 2)