If sodium sulphate is considered to be completely dissociated into cations and anions in aqueous solution , the change in freezing point of water `(DeltaT_(f))` when `0.01` mole of sodium sulphate is dissociated in 1 kg of water is : (`K_(f) = 1.86` K kg `mol^(-1)`)

Options

A. `0.0372K`
B. `0.0558K`
C. `0.0744K`
D. `0.0186K`

Answer

B

Explanation

`Na_(2)SO_(4)to2Na^(+)+SO_(4)^(2-)`
`"van't Hoff factor for "Na_(2)SO_(4)=3`
`DeltaT_(f)=ixxK_(f)xxm" "[becausem=(0.01)/(1)=0.01]`
`3xx1.86xx0.01=0.0558K`