Question
A 5.25% solution of a substance is isotonic with a 1.5% solution of urea (molar mass = 60 g mol–1) in the same solvent. If the densities of both the solutions are assumed to be equal to 1.0 gcm–3, molar mass of the substance will be –
-
90.0g mol–1
-
115.0g mol–1
-
105.0g mol–1
-
210.0 g mol–1
Solution
D.
210.0 g mol–1
Solutions with the same osmotic pressure are isotonic
Let the molar mass of the substance be M
π1 =C1RT=C2RT =π2
So, C1 = C2
As density of the solutions are same
