Answer:
DE2
Explanation: for every one D+2 you need two E-1 because +2=-2
Displaced volume :
<span> Vf - Vi
</span>
77.0 mL - 50.0 mL => 27 mL
Therefore:
d = m / V
d = 521 / 27
d = 19.29 g/mL
Answer:
1.62
Explanation:
From the given information:
number of moles of benzamide 
= 0.58 mole
The molality = 

= 0.6837
Using the formula:

where;
dT = freezing point = 27
l = Van't Hoff factor = 1
kf = freezing constant of the solvent
∴
2.7 °C = 1 × kf × 0.6837 m
kf = 2.7 °C/ 0.6837m
kf = 3.949 °C/m
number of moles of NH4Cl = 
= 1.316 mol
The molality = 
= 1.5484
Thus;
the above kf value is used in determining the Van't Hoff factor for NH4Cl
i.e.
9.9 = l × 3.949 × 1.5484 m

l = 1.62