For solution at atmospheric pressure, `Phi_(S)` (water potential) is equal to

Answer

To solve the question regarding the water potential (Ψ) of a solution at atmospheric pressure, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Water Potential**: Water potential (Ψ) is defined as the potential energy of water in a system compared to pure water, and it is influenced by solute concentration and pressure.

2. **Formula for Water Potential**: The water potential is calculated using the formula:
\[ Ψ = Ψ_s + Ψ_p \]
where:
- Ψ is the water potential,
- Ψ_s is the solute potential,
- Ψ_p is the pressure potential.

3. **Consider Atmospheric Pressure**: At atmospheric pressure, the pressure potential (Ψ_p) is effectively zero. This is because there is no additional pressure being applied to the solution.

4. **Substituting Values**: Since Ψ_p = 0 at atmospheric pressure, we can substitute this value into the water potential formula:
\[ Ψ = Ψ_s + 0 \]
This simplifies to:
\[ Ψ = Ψ_s \]

5. **Conclusion**: Therefore, for a solution at atmospheric pressure, the water potential (Ψ) is equal to the solute potential (Ψ_s).

### Final Answer:
For a solution at atmospheric pressure, \( Ψ = Ψ_s \).

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