Final answer:
No rotation of plane-polarized light by a compound thought to be chiral may indicate the compound is a meso compound or a racemic mixture, with the former being optically inactive due to a symmetry plane, and the latter having no net optical activity due to equal amounts of enantiomers.
Step-by-step explanation:
If there is no rotation of plane-polarized light by a compound in a specific solvent, though thought to be chiral, it may mean several things. The compound could be a meso compound which is achiral despite having chiral centers, due to a plane of symmetry that makes it optically inactive. Another possibility is that the compound is present in the form of a racemic mixture, in which equal amounts of left- and right-rotating enantiomers cancel each other's optical activity. It is unlikely that the compound is chiral and optically active without showing any rotation unless there is no compound present in the solution.