The relative lowering of vapour pressure of a dilute aqueous solution containig non volatile solute is 0.012. The molality of solution is about
relative lowering of vap pressure for non volatile solute :
(p0 - ps ) /p0 = x2 = n2 / n1
putting n1 = 1000/18 moles
we get
n2 = 0.012* 1000/18 =0.6667 moles
and this gives molality of solution i.e 0.6667 m