Answer
(a) meta-disubstitued
(b) para-disubstitued
(c) ortho-disubstitued
Work Step by Step
1. ortho disubstitued benzene has substituents at positions 1 & 2 of the benzene ring. (the substituents to adjacent to each other)
2. meta-disubstitued benzene has substituents at positions 1 & 3 of the benzene ring.
3. para disubstitued benzene has substituents at positions 1 & 4 of the benzene ring. (the substituents are directly opposite to each other)
