Correct Answer - 3
`chi_(solute)=n_(solute)/(n_(solute)+n_(solvent))`
`m=n_(solute)/(Kg_(solvent))`
Since solution is a homogeneous mixture, we can consider any size of solution. If we take `1 kg` of solvent, then
`m=n_(solute)`
and
`n_(solvent)=(1000 g)/(M_(solvent))`
where `M_(solvent)` is the molar mass of solvent. Substuting this result into fraction expression, we get
`chi_(solute)=m/(m+1000/M_(solv))`
`=(mM_(solv))/(mM_(solv)+1000)`