. A solution containing


10 g per dm3 of urea (molecular mass = 60 g mol-1) is isotonic with a 5% solution of a non volatile solute.

The molecular mass of this non volatile solute is

(a)  300 g mol-1 

(b)  350 g mol-1

(c)  200 g mol-1 

(d)  250 g mol-1

 

Best Answer

Solution ||| Suppose the molecular mass of non volatile solute is M

Molar conc. Of urea solution = 10/60 per dm3

Molar conc. Of non volatile solute solution

= 5/M per 100 mL

= 50/M per dm3

For isotonic solution at the same temperature molar concentration are equal

10/60 = 50/M

M = 300g mol-1

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