If some solute is dissolved in pure water, its water potential

Options

A. remains same
B. increases
C. decreases
D. first decreases then increases.

Explanation

To determine how the water potential changes when a solute is dissolved in pure water, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Water Potential**: Water potential (Ψ) is a measure of the potential energy in water and is influenced by solute concentration and pressure. The formula for water potential is given by:
\[ Ψ = Ψ_s + Ψ_p \]
where Ψ_s is the solute potential and Ψ_p is the pressure potential.

2. **Identify Pure Water's Water Potential**: Pure water has a water potential of zero (Ψ = 0) at standard atmospheric pressure. This means there are no solute particles present to affect the water potential.

3. **Add Solute to Pure Water**: When a solute is dissolved in pure water, it introduces solute particles into the solution. This increases the solute concentration.

4. **Effect on Solute Potential (Ψ_s)**: The addition of solute decreases the free energy of water molecules. As a result, the solute potential (Ψ_s) becomes negative. The more solute that is added, the more negative the solute potential becomes.

5. **Calculate the New Water Potential**: Since the pressure potential (Ψ_p) remains zero (assuming no pressure is applied), the overall water potential (Ψ) will now be equal to the solute potential (Ψ_s), which is negative. Therefore, the water potential decreases.

6. **Conclusion**: Thus, when some solute is dissolved in pure water, the water potential decreases and takes on a negative value.

### Final Answer:
If some solute is dissolved in pure water, its water potential decreases and becomes negative.