Which Statement Is NOT Correct? Determination of the Molar Mass

Multiple Choice

Which statement is NOT correct? Determination of the molar mass of an unknown sample by an osmotic pressure measurement requires that

A) the solute dissolved in the solution is pure.
B) the solute is a nonelectrolyte.
C) the molecules of the solute do not pass through the semipermeable membrane.
D) the mass of the solute dissolved in the solution is known in advance.
E) the molar concentration of the solute in the solution is known in advance.