Correct Answer - A
`(n)/(n+N) = 0.2 :. (N)/(n+N) = 0.8`
or `(n)/(N) = (1)/(4)`
or `(n_(I_(2)))/(w_(C_(6)H_(6))) xx M_(C_(6)H_(6)) = (1)/(4)`
`:.` Molality `=(n_(I_(2)))/(w_(C_(6)H_(6))) xx 1000`
`= (1)/(4) xx (1000)/(M_(C_(6)H_(6)))`
or Molality `= (1)/(4) xx (1000)/(78)`
`= 3.2`