Final answer:
PPM stands for parts per million and is used to express the concentration of a solute in a solution. It represents the number of grams of solute per 10^6 grams of solution.
Step-by-step explanation:
PPM stands for parts per million, which is a unit used to express the concentration of a solute in a solution. PPM represents the number of grams of solute per 10^6 grams of solution. It is commonly used for very dilute solutions and can be converted to other concentration units such as molarity or mol/kg solvent.