Answer : The prefix used to name a hydrocarbon that has an eight-carbon parent chain should be, Oct-
Explanation :
The prefix used to name a hydrocarbon that has one, two, three, four, five, six, seven, eight, nine and ten carbon parent chain should be, meth-, eth-, prop-, but-, pent-, hex-, sept-, oct-, non- and dec- respectively.
The naming of alkane is done by adding the suffix -ane, alkene by adding the suffix -ene, alkyne by adding the suffix -yne and carboxylic acid by adding the suffix -oic acid.
If two or more similar alkyl groups are present in a compound, the words di-, tri-, tetra- and so on are used to specify the number of times of the alkyl groups in the chain.
Hence, the prefix used to name a hydrocarbon that has an eight-carbon parent chain should be, Oct-