A solution containing 10 g per ( dm ^3 ) of urea (molecular mass (=60 ~g ~mol ⁻¹ )) is isotonic with a (5 % ) solution of a nonvolatile solute. The molecular mass of this nonvolatile solution is:

Step-by-step solution

The molar concentration of urea solution = 10 g / d m^3 Mol. wt. of urea = 10 60 M = 1 6 M Molar concentration of 5 % nonvolatile solute aligned & = 50 ~g / dm ^3 mol. wt. of non - volatile solute & = 50 ~m M aligned Both solutions are isotonic to each other; therefore, 1 6 = 50 m m=50 6=300 ~g ~mol ⁻¹ Caution 10 ~g per dm ^3 of urea is isotonic with 5 % solution of a non-volatile solute. Hence, osmosis cannot occur between the two solutions. Thus, their molar concentrations are equal to each other.