A) 1% glucose
B) 1% NaCI
C) 1% sucrose
D) 1% \[CaC{{l}_{2}}\]
Correct Answer: B
Solution :
Elevation in boiling point is colligative property, it depends upon number of ions or molecules or particles. Glucose and sucrose does not dissociate so \[n=1\] for these solutions while for \[NaCl,\,\,n=2\]and for \[CaCl,\,\,n=3\]. 1% solution means 100 g solution contains 1 g solute (glucose or \[NaCl\]or sucrose or \[CaCl\]). \[{{w}_{2}}=1\,\,g,{{w}_{1}}\] (solvent) = 99 g \[\Delta {{T}_{b}}=\frac{i\times {{k}_{b}}\times {{W}_{2}}\times 1000}{{{M}_{2}}\times {{W}_{1}}}\] For glucose. \[\Delta {{T}_{b}}=\frac{1}{180}=0.0056\] (because \[{{k}_{b}},{{w}_{2}},{{w}_{1}}\] same for all the cases) For sucrose, \[\Delta {{T}_{b}}=\frac{1}{342}=0.00292\] For NaCI, \[\Delta {{T}_{b}}=\frac{2}{58.5}=0.0342\] For \[CaC{{l}_{2}}\], \[\Delta {{T}_{b}}=\frac{3}{111}=0.0270\] Hence 1% NaCI solution has the highest boiling point.
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