When 116. g of urea (CH4N2O) are dissolved in 1500. g of a certain mystery liquid X, the freezing point of the solution is 6.4°C lower than the freezing point of pure X. On the other hand, when
116.
g
of iron(III) nitrate
FeNO33
are dissolved in the same mass of
X
, the freezing point of the solution is
5.8°C
lower than the freezing point of pure
X
.