Water potential of a solution is always

Options

A. less than zero
B. zero
C. more than zero
D. unity

Answer

### Step-by-Step Solution:

1. **Understanding Water Potential**: Water potential (Ψw) is a measure of the potential energy of water in a system. It determines the direction of water movement and is influenced by solute concentration and pressure.

2. **Pure Water Reference**: The water potential of pure water at standard temperature and pressure is defined as zero (Ψw = 0). This serves as the baseline for comparing other solutions.

3. **Effect of Solutes**: When solutes are added to water, the water potential decreases. This is because the presence of solutes reduces the concentration of free water molecules, which in turn lowers the kinetic energy of the water.

4. **Negative Water Potential**: Since the maximum water potential is zero (pure water), any solution containing solutes will have a water potential that is less than zero. The more solute that is added, the more negative the water potential becomes.

5. **Conclusion**: Therefore, the water potential of a solution is always less than zero, as it is influenced by the presence of solutes which decrease the water potential from the baseline of pure water.

### Final Answer:
The water potential of a solution is always **less than zero**.

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