1.

What will be the precentage of dimerisation of 61 g of benzoic acid in 1000 g of a solvent prodicing a depression is freezing point of `2^(@)C` ? (Given `K_(f)` for solvent =6 K kg `mol^(-1)`)A. 0.72B. 0.67C. 0.43D. 0.28

Answer» Correct Answer - b
`DeltaT_(f)=ixxK_(f)xxmori=(DeltaT_(f))/(K_(f)xxm)`
`m=W_(B)/(M_(B)xxW_(A))=((61g))/((122"g mol"^(-1))xx(1kg))=0.5"mol kg"^(-1)`
`i=((2K))/((6 "K kg mol"^(-1))xx(0.5"mol kg"^(-1)))=0.67`
`alpha=((1-i))/((1-1/n))=((1-0.67))/((1-0.5))=0.33/0.5=66%`


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