150 mL of `C_(2)H_(5)OH`(density = 0.78 g `mL^(-1)`is diluted to one litre by adding water, molality of the solution is

Options

A. 2.54
B. 11.7
C. 2.99
D. 29.9

Answer

C

Explanation

`m=(W_(2) xx 1000)/(M_(2) xx W_(1)(g))`
150 mL `C_(2)H_(5) OH=150 xx 0.78 g =117.0 g=W_(2)`
Water =850 g = `W_(2)`=46 g `"mol"^(-1)
`"Molality"= `(117 xx 1000)/ (46 xx 850)=2.99`