`0.6%` solution of urea and `1.8%` solution containing a solute (A) are isotonic with each other. Calculate the molecular weight of the solute (A).

Explanation

`x=0.6% y=1.8%, M_(x)="urea" (60 g "mol"^(-1)),M_(y)=?`
`(x)/(100)xx(100)/(M_(x))=(y)/(100)xx(100)/(M_(y))=(x)/(M_(x))=(y)/(M_(y))`
`M_(y)=(y xx M_(x))/(x)=(1.8xx60 g "mol"^(-1))/(0.6)`
`=180 g "mol"^(-1)`