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How many moles of sucrose should be dissolved in 500 g of water so as to get a solution which has a difference of `103.57^(@)C` between boiling point and freezing point :- `(K_(f)=1.86" K kg mol"^(-1), K_(b)="0.52 K kg mol"^(-1))`A. `0.5` molesB. `0.9` molesC. `0.75` molesD. `0.65` moles |
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Answer» Correct Answer - C `because" "T_(b)=T_(b)^(@)=K_(b)xxm" …(i)"` `" "T_(f)^(@)-T_(f)=K_(f)xxm" …(ii)"` `"(i) equation "+" (ii) equation"` `(T_(b)-T_(f))+(T_(f)^(@)-T_(b)^(@))=m(K_(b)-K_(f))` `103.57-100=m(1.86+0.52)` `(3.57)/(2.38)=(n)/(500)xx1000` `0.75" moles"` |
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