We must to know:
Cm = molarity = niu / Vs, when the niu = no. of moles and Vs = Volume of solution
the no. niu = mass / molecular mass of substance
molecular mass of C8H8 = 12x8+8x1 = 104 g/mol
=> niu = 1,5 / 104 = 0,0144 moles C8H8
=> Cm = 0,0144/0,225 = 0,06 mol/L
Cmm = molality = niu (C8H8) / mass of solvent (kg)
=> p = mass / V => mass (solvent) = p x V
=> 225 x 1,02 = 229,5 g solvent = 0,2295 kg solvent
=> Cmm = 0,0144 / 0,229,5 = 0,063
