The density of `3M` solution of `NaCl` is `1.25 g mL^(-1)`. The molality of the solution is

Options

A. 260 m
B. 2.18 m
C. 2.79 m
D. 3.00 m

Answer

C

Explanation

The relation between molarity(M) and molality(m) is `d=M((1)/(m)+(M_(2))/(1000)), M_(2)="Mol"`. mass of solute
On putting value
`1.252=3((1)/(m)+(58.5)/(1000))`
on solving m = 2.79