What is the fraction of the solute in a `1.00` m aqueous solution ?

Options

A. `0.177`
B. `1.770`
C. `0.0354`
D. `0.0177`

Answer

D

Explanation

Molality (m) `=(1000xx n)/(N xx M)`
where, n = number of moles of solute
N = number of moles of solvent
= molar mass of solvent
Given, m = 1
`therefore 1=(1000xx n)/(N xx 18)`
`rArr (n)/(N)=(18)/(1000)`
or `(n)/(n+N)=(18)/(1018)=0.0177`
Alternate Method `N=(1000)/(18)=55.5` mol
n = 1
[`because 1` m solution implies that 1 mole of solute is present in 1 kg or 1000 g water]
`therefore` Mole fraction of solute
`=(n)/(n+N)=(1)/(1+55.5)=0.0177`