Lowering of vapour pressure of an aqueous solution of a non-volatile, non-electrolyte 1 M aqueous solution at 100oC is

1 M aqueous solution contains 1 mole of solute in 1000 g (55.5 moles) of water.                       xB=11+55.5=156.5                                      po=760 torr at 100oC                             ∆ppo=xB,∆p=poxB=760×156.5=13.45 torr