The percentage composition by mass of an aqueous solution of a solute (molecular mass 150 which boils at 373.26 is `(K_(b) = 0.52)`

Options

A. 5
B. 15
C. 7
D. none of the above.

Answer

C

Explanation

`Delta T_(b) = K_(b) xx m, i.e, 0.26 = 0.52m "or" M = 0.5`
`m = (W_(2) xx 1000)/(M_(2) xx W_(1)(g)) :. 0.5 = (W_(2) xx 100)/(150 xx 1000)`
`W_(2) = 150 xx 0.5 = 75 g `
%age by mass `=75/1075 xx 100 = 7% "approx".`