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1)

 MX2  dissociates into M2+ and X-  ions in an aqueous solution, with a degree of dissociation ( α) of 0.5. The ratio of the observed depression of freezing point of the aqueous solution  to the value of the depression of freezing point in the absence of ionic dissociation is 


A) 4

B) 3

C) 1

D) 2

Answer:

Option D

Explanation:

MX2M2++2X

 van't Hoff factor for any salt can be calculated using equation

               i=1+α(n1)

 where ,n= number of constituent ions

         i(MX_{2})=1+\alpha(3-1)

                                  = 1+2\alpha

\frac{(\triangle T_{f})observed}{(\triangle T_{f})teoretical}=i=1+2\alpha

   \therefore        i=1+2 x0.5

                       i=2