Potato slices are immersed in a series of solutions of different osmotic concentrations. No change in volume or weight is observed with slices in a \[0.3\]M solution. Therefore the osmotic concentration of vacuolar sap is,
A. \[0.3\]M
B. Greater than \[0.3\]M
C. Less than \[0.3\]M
D. Not related at all to the outside solution

Hint: Osmotic concentration, erstwhile called osmolarity, is that the life of matter concentration, outlined because of the range of osmoles (Osm) of matter per metric capacity unit (\[L\]) of answer (osmol/\[L\] or Osm/\[L\]). The osmolarity of an answer is typically expressed as Osm/\[L\] (pronounced "osmolar"), within the same approach that the concentration of an answer is expressed as "M" (pronounced "molar").

Complete answer:
During diffusion, water flows from an area of its higher concentration (dilute solution) to an area of its lower concentration (concentrated solution), across a tissue layer.
If there's no movement of water across the membrane, it suggests that the two solutions have identical diffusion concentrations i.e., they're isotonic.
For example, during this case, we tend to conclude that the diffusion concentration of cell sap is \[0.3\]M, as a result of the potato slice neither gains water through endosmosis nor loses water through exosmosis.

So, A is the correct option.

Additional info: An solution is one that has identical osmolarity, or substance concentration, as another answer. If these two solutions square measure separated by a tissue layer, water can flow in equal elements out of every answer and into the opposite.

Note:
Whereas concentration measures the number of moles of matter per unit volume of an answer, osmolarity measures the number of osmoles of matter particles per unit volume of an answer. This price permits the measuring of the force per unit area of an answer and therefore the determination of however the solvent can diffuse across a tissue layer (osmosis) separating two solutions of various diffusion concentration.