Question

which is a way to express concentration of a solution?
○ parts per billion
○ moles
○ molar mass
○ force per square meter

Explanation:

• "parts per billion" is a unit to express the concentration of a solution, representing the amount of solute relative to the solution.
• "moles" is a unit of amount of substance, not a concentration unit.
• "molar mass" is the mass of one mole of a substance, not for concentration.
• "force per square meter" is the unit of pressure (Pascal), unrelated to solution concentration.

Answer:

A. parts per billion