`20`g of a binary electrolyte(mol.wt.=`100`)are dissolved in `500`g of water.The freezing point of the solution is `-0.74^(@)CK_(f)=1.86K "molality"^(-1)`.the degree of ionization of the electrolyte is

Options

A. `0%`
B. `100%`
C. `75%`
D. `50%`

Answer

A

Explanation

`DeltaT=(1000xxK_(f)xxw)/(mxx500)`
`0.74=(1000xx1.86xx20)/(mxx500)`
`mxx100`
`"Actual molecular mass"=100rArri=(100)/(100)=1+alpha`
`alpha=0`
`:.` The degree of ionisation of the electrolyte is 0%.