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

Answer

D

Explanation

`Na_(2)SO_(4) rarr 2Na^(+) + SO_(4)^(2-)`
Hence, i=3 (for complete dissociation)
`Delta T_(f) = i K_(f) m=3 xx 1.86 xx 0.01/(1kg) = 0.0588^(@)C`