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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 |
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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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