Index fossils (also known as guide fossils, indicator fossils or zone fossils) are fossils used to define and identify geologic periods (or faunal stages).
It depends on what kind of solution is referred as 0.65 M. If the solution where the red blood cell is present is hypertonic, the red blood cell will shrink. If the solution is hypotonic, the red blood cell will expand. If the solution is isotonic, the red blood cell will not expand or shrink.
