If 1 gm of steam at 1000 C is sent into 1 gm of ice at 00 C, final condition of the mixture is
Heat required to melt ice and to convert into water at 100∘C=1×80+1×1×100=180 cal. This heat is provided by steam of mass m by condensing then, 180 cal =m×540 cal m=13 gm i.e. 23gm of steam is uncondensed. So the final mixture is 43gm of water at 100∘C.