2.5 liters of 1 M NaOH solution is mixed with another 3 liters solution of 0.5 M NaOH. The molarity of resultant solution is:

Mole of NaOH in I solution = 2.5 × 1 = 2.5Mole of NaOH in II solution = 3 × 0.5 = 1.5Total mole = 2.5 + 1.5 = 4.0∴Molarity x total volume = Total mole∴M=45.5=0.73M