The number of moles = volume * molarity.
Volume = 500/1000 of Nacl solution.
Volume = 0.5 of Nacl
Hence number of moles = 0.5 * 2 = 1.
To calculate how many milliliters of a 4.0 m nacl solution.
We have number of moles = volume * molarity.
Hence volume = number of moles /molarity
Volume = 1 / 4 = 0.25L = 2500mL