If a compound AB dissociates to the extent of 75 % in an aqueous solution, the molality of the solution which shows a 2 . 5 K rise in the boiling point of the solution is ___ molal. (Rounded-off to the nearest integer) K b = 0 . 52 K kg mol - 1 .

Step-by-step solution

α = 0 . 75 , n = 2 i = 1 - α + n α = 1 - 0 . 75 + 2 × 0 . 75 = 1 . 75 Δ T b = ik b m or 2 . 5 = 1 . 75 × 0 . 52 × m or, m = 2 . 5 1 . 75 × 0 . 52 = 2 . 74 ∴ nearest integer answer will be 3