A) 60
B) 80
C) 72
D) 63
E) 98
Correct Answer: C
Solution :
Since the two solutions are isotonic, they must have same concentrations in moles/litre. For glucose solution, concentration \[=5\text{ }g/100\text{ }c{{m}^{3}}\] (given) \[=50g/L\] \[\therefore \] \[\frac{50}{180}=\frac{20}{M}\] Or \[M=72\] (\[\because \]Molar mass of glucose\[=180\text{ }g\text{ }mo{{l}^{-1}}\]) For unknown substance, concentration \[=2\text{ }g/100\text{ }c{{m}^{3}}\] (given) \[=20g/L=\frac{20}{M}mol/L\] \[\therefore \] \[\frac{50}{180}=\frac{20}{M}\] or \[M=72\]You need to login to perform this action.
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