Six students (D, E, F, G, H and I) sit in a linear row

Solution

F sits third from extreme left end of row. One person sits between D and F.  H sits third to the right of G. G doesn’t sit adjacent to E or I. We get D sits either at extreme left or second from extreme right end of row. H sits at extreme left end of row. Either I or E sits at extreme right end of row. The final arrangement is as follows: Either I or E sits second to the left of G. H         I/E       F          G         D         E/I