5 g of Na₂SO₄ was dissolved in x g of H₂O. The change in freezing point was found to be 3.82^oC. If Na₂SO₄ is 81.5% ionised, the value of x

(K_f for water=1.86^oC kg mol⁻¹) is approximately :

(molar mass of S = 32 g mol⁻¹ and that of Na = 23 g mol⁻¹)

The freezing point of benzene decreases by 0.45⁰C when 0.2 g of acetic acid is added to 20g of benzene. If acetic acid associates to form a dimer in benzene, percentage association of acetic acid in benzene will be: (K_f for benzene = 5.12 K kg mol^–1)

An aqueous solution of a salt MX₂ at certain temperature has a van’t Hoff factor of 2. The degree of dissociation for this solution of the salt is :

The solubility of N₂ in water at 300 K and 500 torr partial pressure is 0.01 g L⁻¹. The solubility (in g L⁻¹) at 750 torr partial pressure is :