1.

2.25 g of a Non volatile substance dissolved in 250 g of `C_6H_6`.This solution shows depression in F.P. by 0.256 K.Which of the following is/are correct : Given that : (`K_b` and `K_f` for `C_6H_6` is 2.53 `"Kmolal"^(-1)` and `5.12 "Kmolal"^(-1),BP` of `C_6H_6=353.3K`)A. Molar mass of substances is =180B. B.P. of solution is =180C. Relative lowering in vapour pressure of solvent =0.0038D. All are not correct

Answer» Correct Answer - ABC
`DeltaT_f=mxxK_f=(g.wt)/(M.M)xx1000/((g.wt.)_"solvent")xxK_f`
0.256=`2.25/(M.M)xx1000/250xx5.12`
M.M=180 g/mol
`DeltaT_b=mxxK_b=(g.wt)/(M.M)xx1000/((g.wt.)_"solvent")xxK_b =2.25/(180)xx1000/250xx2.53=0.1265`
B.P. of solution =353.3+0.1265=353.425 K
`(DeltaV.P.)/P_("solvent")^@=X_B=n_B/(n_A+n_B)=(2.25/180)/(2.25/180+250/75)=0.00388`.


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