The relative lowering of vapour pressure of a solution containing 6g of urea dissolved in 90g of water is

Solvent – water, solute – urea

Wt. of urea  $={\mathrm{W}}_1=6\mathrm{g}$               GMW of urea = ${\mathrm{M}}_1=60\mathrm{g}$

Wt of water = ${\mathrm{W}}_2=90\mathrm{g}$        GMW of water =${\mathrm{M}}_2=18$

According to Raoult’s law relative lowering of vapor pressure (R.L.V.P) is

R.L.V.P$=\frac{{\mathrm{W}}_1}{{\mathrm{M}}_1}\times \frac{{\mathrm{M}}_2}{{\mathrm{W}}_2}$

$=\frac{6}{60}\times \frac{18}{90}$

$=\frac{1}{50}=0.02(\mathrm{Near} \mathrm{by})$