There are a number of ways
to express concentration of a solution. This includes molarity. Molarity is
expressed as the number of moles of solute per volume of the solution. We can calculate as follows:
Mass of KOH = 1.50 mol KOH/ L solution (2.50 L) (56.11 g/mol) = 210.41 g KOH
Therefore, the first option is the answer.