Water potential is maximum in case of:

Question

Accepted Answer

The correct option is 1:

Water potential (Ψw) is a measure of the potential energy of water per unit volume relative to pure water in reference conditions. It quantifies the tendency of water to move from one area to another due to osmosis, gravity, mechanical pressure, or matrix effects. By convention, the water potential of pure water at standard atmospheric pressure and at a given temperature is defined as zero. When solutes are added to pure water, they reduce the free energy of water, thereby lowering its water potential. This reduction is primarily due to the solute potential (Ψs), which is always negative or zero. Therefore, pure water, having no solutes, possesses the highest possible water potential, which is zero. Any solution containing solutes will have a water potential less than zero (i.e., a negative value).

The incorrect option is 2: 2% glucose.
Adding 2% glucose to water introduces solutes, which will lower the water potential from that of pure water. While it is a relatively dilute solution, its water potential will be negative, making it lower than the water potential of pure water.

The incorrect option is 3: 10% glucose.
A 10% glucose solution has a higher concentration of solutes than a 2% glucose solution. Consequently, it will have a more negative (lower) water potential compared to the 2% glucose solution and significantly lower than pure water, as more solute particles restrict the free movement of water molecules.

The incorrect option is 4: 10% NaCl.
Sodium chloride (NaCl) dissociates into two ions (Na+ and Cl-) in water, effectively doubling the number of solute particles compared to an equal molar concentration of a non-dissociating solute like glucose. A 10% NaCl solution will have a very high concentration of solute particles, leading to a much more negative (and thus lowest among the given options) water potential.