Question

The water potential and osmotic potential of pure water are

• A. 100 and 200
• B. zero and 100
• C. 100 and zero
• D. zero and zero

Answer 1

The Correct Option is D

To understand the water potential and osmotic potential of pure water, we must first understand the concepts of these terms:

• Water Potential (\( \Psi_w \)): This is a measure of the potential energy of water in a system compared to pure water, when both are at the same temperature and pressure. It indicates the tendency of water to move from one area to another. The water potential of pure water is defined as zero (\(\Psi_w = 0\)) at a standard temperature and pressure.
• Osmotic Potential (\( \Psi_s \)): This is the potential of water molecules to move across a semi-permeable membrane due to solute concentration differences. For pure water, there are no solutes present, hence the osmotic potential is also zero (\(\Psi_s = 0\)).

Thus, the water potential and osmotic potential of pure water are both zero. This serves as the baseline for comparison when calculating these potentials in solutions with different concentrations.

Conclusion: The correct answer is zero and zero for both the water potential and osmotic potential of pure water.

Let's evaluate the options:

1. 100 and 200: Incorrect, as explained, both potentials for pure water are zero.
2. Zero and 100: Incorrect, osmotic potential for pure water is zero, not 100.
3. 100 and zero: Incorrect, water potential for pure water is zero, not 100.
4. Zero and zero: Correct, both water potential and osmotic potential are zero for pure water.