The number of particles of a solute in a solution is described by its . The ability of a solution to affect the fluid volume in a cell is referred to as its .

The number of particles of a solute in a solution is described by its osmolarity. The ability of a solution to affect the fluid volume in a cell is referred to as its tonicity.

Explanation:

When concentration of a solution is expressed as total number of solute particles in a liter of solvent is called osmolarity.

For example, one mole of a glucose will not dissolve in 1 liter of solution. This means that a solution of 1 mol/L of glucose will have an osmolarity of 1 Osm/L.

The concentration of solute particles relative to that of another solution present on the opposite side of a cell membrane is called tonicity.

Basically, it is the ability of extracellular solution to allow the water move in and out of the cell by osmosis.

Thus, we can conclude that the number of particles of a solute in a solution is described by its osmolarity. The ability of a solution to affect the fluid volume in a cell is referred to as its tonicity.