Answer
See the following structure for each compound.
Work Step by Step
Question a) Look at the name of the compound. The compound is a monosubstituted benzene as the name suggests butyl benzene. It means a butyl (-CH2CH2CH2CH3) is present as a substitute in the benzene ring. One Hydrogen of benzene is substituted by this butyl group.
b) By looking at the name of compound we found that this is a disubstituted benzene where a ethyl (-CH2CH3) group and a Iodine (-I) group are present in the benzene ring in 1 and 2 position of the benzene ring respectively. (see below how to find position in the benzene ring when more than one substitute are present.)
c) para means two substitutes are present in opposite direction (1,4 position) in the benzene ring. Here, two methyl (-CH3) groups are present in para position i.e. opposite to each other i.e. 1,4 position in the benzene ring.