Question

Which unit can be used to express the concentration of a solution?

Answer 1

Answer: (3) ppm

Explanation: Concentration is defined as the amount of solute dissolved in a known amount of the solvent or  a solution.

Parts per million (ppm) is used to express the concentration when a very small quantity of solute is present in a large quantity of the solution. It is defined as the mass of solute present in one milion $(10^6)$ parts by mass of the solution.

$ppm=\frac{\text {mass of Solute}}{\text {Mass of solution}}\times 10^6$

L/s is used to express flow rate.

J/g is used to express energy per unit mass.

kPa is used to express pressure.

Answer 2

Also to clarify further, L/s is a unit of flow rate, J/g is a unit of energy per unit mass, and kPa is a unit of pressure known as kilo pascals which is equivalent to 1000 pascals