Answer
B
Work Step by Step
Per kg of mixture:
Mass of acetic acid:
$5\%\times 1\ kg = 0.05\ kg=50\ g$
The molar mass of acetic acid:
$1.008|_H\times4+12.011|_C\times2+15.999|_O\times2=60.052\ g/mol$
Number of mols of acetic acid:
$50\ g\div60.052\ g/mol=0.833\ mol$
Mass of water:
$(100-5)\%\times1\ kg=0.95\ kg$
Molality:
$0.833\ mol\div0.95\ kg=0.876\ molal$
