Question

An osmometer is filled with 0.5 M solution of NaCl in water. In which of the following solutions it must be immersed in order to make it shrink?
A. 0.5 M solution
B. 0.05 M solution
C. Distilled water
D. 0.75 M solution

Answer 1

Endosmosis is the condition when the solute moves from the lower concentration to the higher concentration. It is an ancient technique used to make a person vomit also. Our tissues in the body have less solute. The osmosis will occur to balance them. This process can occur in the artificially created medium also.

Step by step answer: A cell undergoes osmosis according to the environment in which it is present. When the water moves inside the cell, it is endosmosis. Whereas the expel of water from the cell is exosmosis.
Solutions are made of different concentrations. Their net movement depends on the concentration of the solutes. The equilibrium is tried to be maintained by diffusing the solutes so that there is no net movement of them at last. The isotonic solution is preferred over hypotonic and hypertonic.
Let’s understand this with an example – There are solutions with different concentrations of solute and solvent- when the high solute concentrated solution A Is separated from the low concentrated solute solution B. Then the A is hypertonic and B is hypotonic. Here the net movement will be from the hypotonic to the hypertonic solution.
In this question, we want the osmometer to shrink thus we need the exosmosis should take place. For this, we will need a more concentrated solution outside the osmometer so that the water from the osmometer can leave it and enter the surface to make it shrink.
Option A: 0.5 M solution: This solution is isotonic to the osmometer so there will be no net movement of solvent or solute.
Option B: 0.05 M solution: the solution here is very less concentrated to do exosmosis in the osmometer, rather the endosmosis will take place.
Option C: Distilled water: Distilled water has no concentration, this will lead to endosmosis.
Option D: 0.75 M solution: This more concentrated solution will help in the shrinking of the osmometer as the water will leave causing exosmosis.
So the answer is option D: 0.75 M solution

Note: Osmosis is the spontaneous movement of a solvent through a selective semi-permeable membrane. It helps to maintain the gradient on both sides of the membrane. Pure water has a very high water potential. Plants cells take in water by osmosis until the cell wall pushes back the cell contents with equal pressure.