A) \[0.555\,mol\,k{{g}^{-1}}\]
B) \[5.55\times {{10}^{-4}}\,mol\,k{{g}^{-1}}\]
C) \[8.33\times {{10}^{-4}}\,mol\,k{{g}^{-1}}\]
D) \[33.3\,mol\,k{{g}^{-1}}\]
Correct Answer: C
Solution :
[c] \[1\,d{{m}^{3}}=100\,c{{m}^{3}}=1\,L=1\,kg\] \[0.400\,d{{m}^{^{3}}}\] of \[{{H}_{2}}O\] at STP=\[0.400\,kg\] of \[{{H}_{2}}O\] (Density=1.0 g\[c{{m}^{-3}}\]) Moles of urea =\[\frac{0.0200}{60}mol\] (Molar mass of\[N{{H}_{2}}\,CON{{H}_{2}}=60gmo{{l}^{-1}}\]) \[\therefore \]Molality \[=\frac{\text{Moles}\,\text{of}\,\text{solut}\,\text{(urea)}}{\text{kg}\,\text{of}\,\text{solvent}}=\frac{0.020/60}{0.400kg}\] \[=8.33\times {{10}^{-4}}mol\,k{{g}^{-1}}\]
You need to login to perform this action.
You will be redirected in
3 sec
