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Answer 1 · 2017-02-04T03:12:58

The depression of freezing point of solvent #DeltaT_f# is related with the molality #m # of the solute as follows

#color(blue)(DeltaT_f=-i*K_f*m..........[1])#

where

#K_f->"cryoscopic constant "=1.853Kkg"/mol for water"#

#m->"molality of the soute"=0.100#

#i->" van't hoff factor"=1+alpha#

#alpha->"degree of dissociation"=1.32%=0.0132#

Replacing i by #1+alpha# the equation [1] becomes

#color(green)(DeltaT_f=-(1+alpha)*K_f*m)#

#color(green)(=>DeltaT_f=-(1+1.0132)*1.853*0.1K~~-0.188K)#

So expected freezing point will be

#color(red)("Expected freezing point"=(273-0.188)K=272.812K)#