Question

Which of the following has the highest water potential?
A.1M salt solution
B. 1M sugar solution
C. Distilled water
D. 1M sugar solution with 2-3 bars pressure

Answer 1

Hint: Distilled water always has the highest water potential because it has no solute dissolved in it and also the pressure on the system is zero.
As we keep on adding a solute to water, it's water potential decreases. The solute potential always has a negative value and an increase in solute will make the water potential low in the solution.
So, the highest water potential will be of pure water.

Complete answer:
Option (A) is 1M saltwater
If the flow is not restricted, water will move from an area of higher water potential to an area of lower water v potential. A common example of this is water with dissolved salt, for example, seawater or the fluid in a living cell. The water potential of these solutions is negative in relation to the pure water reference.

Option (B) is a 1M sugar solution
In the case of sugar water, it has a semi permeable membrane, water molecules can cross the sugar water but the sucrose molecules are too large to cross through it. In this case, the water solution will move from a lower concentration of solutes to a higher concentration of solutes. So, the Sugar solution has a low water potential. It doesn’t have many water molecules.

Option (C) is Distilled water
The largest water potential that any volume of water can have if the standard atmospheric pressure is being applied to that particular volume of water, is defined as 0. This is the water potential of distilled water. Distilled water has the greatest potential to move, and displace any other object.

Option (D) is 1M sugar solution with 2-3 bars pressure
A solution will have a lower and more negative water potential in comparison to pure water. Further, the more the solute molecules, the more negative the solute potential will be. The osmotic potential has important implications for many living organisms. The water potential of this solution will be negative.

So, the correct answer is an option (C) - Distilled water.

Note: Distilled water is water that is being boiled into vapor and condensed back into a liquid state in a separate container. Impurities in the original water that do not boil below or near the boiling point of water remain in the original container itself. Thus, distilled water is one type of purified water.