depression in freezing point for 1 molar concentration of Urea, 1 molar concentration of glucose and 1 molar concentration of NaCl are in the ratio
Since all the 3 have the same concentration the ratio of the depression in freezing point will be equal to that of vant hoff facto.
Where, van't Hoff factor is the number of molecules, that on average result upon solvation of compound in solution.
Urea is non-electrolyte so, i=1
Glucose also has i = 1
NaCl gives Na+ and cl- so, i=2 (add the ions)
We know that Tf=iKf⋅m (where Kf and m are equal in all).
For Urea Tf = 1 x 1m x K f= 1Kf
For Glucose Tf = 1 x 1m x K f= 1Kf
For NaCl Tf = 2 x 1m x K f= 2Kf
Therefore the ratio of the depression in freezing point is 1:1:2 ( option 1)