Question

The water potential of pure water is:

• A. One
• B. More than one
• C. Zero
• D. Less than zero

Hint:

Water potential decreases with the addition of solutes, becoming more negative.

Answer 1

The Correct Option is C

The water potential of pure water is Zero.

(A) One - Incorrect: Water potential is not measured on a scale of 0 to 1.

(B) More than one - Incorrect: Pure water's potential is defined as the zero reference point.

(C) Zero - Correct: By definition, pure water at standard temperature and pressure has Ψ = 0 MPa.

(D) Less than zero - Incorrect: This would indicate negative pressure/solute potential, which pure water lacks.

The correct answer is (C) Zero, as pure water serves as the reference standard (Ψ_water = 0 MPa) in water potential calculations.

Answer 2

The water potential (Ψw\Psi_wΨw​) of a solution is a measure of the potential energy of water and how it moves. It is determined by both solute potential and pressure potential.

For pure water, there are no solutes, and the pressure potential is zero (in an open system), so the water potential is also zero.

Option (C) is correct as pure water has a water potential of zero.