Suspensions

Correct answer: A. Sand does not dissolve uniformly in water

A true solution forms when the solute dissolves at the particle level and becomes uniformly distributed throughout the solvent. Sand is insoluble in water, so its grains remain separate, may be seen, and can settle on standing. Water is liquid and sand is solid; their states are not the reason that the mixture is not a solution.

Correct answer: A. Solution is homogeneous, particles may be visible in suspension

A true solution is homogeneous: its dissolved particles are too small to be seen separately and remain distributed throughout the solvent. A suspension is heterogeneous; its larger particles may be visible, settle on standing, or be separated by filtration. Solutions can be solid, liquid or gaseous, and they always contain a solvent, so the other statements are false.

Correct answer: A. Because sand does not dissolve and spread uniformly in water

A true solution forms when solute particles dissolve and become uniformly distributed throughout the solvent at the particle level. Sand does not dissolve in water; its comparatively large particles remain separate and may settle at the bottom. Water can act as a solvent, but every solid is not soluble in it. Thus option A correctly explains why sand and water do not form a true solution.

Correct answer: A. Because particles remain uniformly distributed in a solution

A true solution is homogeneous, so its solute particles remain uniformly dispersed and do not settle under ordinary conditions. Settling indicates relatively large particles and non-uniform composition, characteristics associated with a suspension or another heterogeneous mixture. A solution can contain solid solute and always has a solvent, so the other reasons are incorrect.