A 5.25% solution of a substance of a substance is isotonic with a 1.5% solution of urea (molar mass of 60 g `mol^(-1)`) in the same solvent. If the de
A 5.25% solution of a substance of a substance is isotonic with a 1.5% solution of urea (molar mass of 60 g `mol^(-1)`) in the same solvent. If the densities of both the solutions are assumed to be equal to 1.0 g `cm^(-3)`, molar mass of the substance will be :
A. 210.0 g `mol^(-1)`
B. 90.0g `mol^(-1)`
C. 115.0 g `mol^(-1)`
D. 105.0 g `mol^(-1)`
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Correct Answer - a
For the isotonic solutions
`pi_(1)=pi_(2)orC_(1)RT=C_(2)RT`
`W_(("urea"))/M_(("urea"))=W_("substance")/M_("substance")`
`((1.5g))/((60g mol^(-1)))=((5.25g))/M`
`M=((5.25 g)xx(60 g mol^(-1)))/((1.5g))`
`=210.0 g `mol^(-1)`
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