Which statement about diluted solutions is false? When a solution is diluted A. the concentration of the solution decreases.
B. the molarity of the solution decreases.
C. the number of moles of solute remains unchanged.
D. the number of moles of solvent remains unchanged.

C. The number of moles of solute remains unchanged.

(Since my answer contradicts the other one here, let me reassure you that my answer is correct by stating that I’m currently doing my Ph. D. in Chemistry.)

A diluted solution is one in which the concentration of a dissolved solid (called the solute) is decreases via the addition of excess solvent. This means that A is a true statement.

Since molarity is a measurement of concentration, based on the conclusion for A, B is also a true statement.

For a given solution, excess solvent is added but the amount of solute present isn’t affected. This means that the number of solute moles is constant and the number of solvent moles is not; C is a true statement, whereas D is false.

Hope this helps!

Solubility would be your answer.