Answer
B and B
Work Step by Step
The molar mass of water:
$1.008|_H\times 2+15.999|O=18.015\ g/mol$
The number of mols of water:
$270\ g\div18.015\ g/mol=14.988\ mol$
The molar fraction of urea:
$1.0/(1.0+14.988)=0.0625$
Molality:
$1.0\ mol\ urea/0.27\ kg\ water=3.70\ molal.$
