A `5% `solution of cane sugar (molar mass 342) is isotonic with 1% of a solution of an unknown solute. The molar mass oftmknown solute in g/mol is :

Options

A. `171.2`
B. `68.4`
C. `34.2`
D. `136.2`

Answer

D

Explanation

For isotonic solutions
`pi _(1) =pi_(2)`
`C_(1) =C_(2)`
`(5//342)/(0.1) =(1//M)/(0.1)`
`(5)/(342) =1/M`
`impliesM =(342)/(5) implies 68.4` gm/mol