Answer: CoBr3 < K2SO4 < NH4 Cl
Justification:
1) The depression of the freezing point of a solution is a colligative property, which means that it depends on the number of particles of solute dissolved.
2) The formula for the depression of freezing point is:
ΔTf = i * Kf * m
Where i is the van't Hoof factor which accounts for the dissociation of the solute.
Kf is the freezing molal constant and only depends on the solvent
m is the molality (molal concentration).
3) Since, you are assuming equal concentrations and complete dissociation of the given solutes, the solute with more ions in the molecular formula will result in the solution with higher depression of the freezing point (lower freezing point).
4) These are the dissociations of the given solutes:
a) NH4 Cl (s) --> NH4(+)(aq) + Cl(-) (aq) => 1 mol --> 2 moles
b) Co Br3 (s) --> Co(3+) (aq) + 3Br(-)(aq) => 1 mol --> 4 moles
c) K2SO4 (s) --> 2K(+) (aq) + SO4 (2-) (aq) => 1 mol --> 3 moles
5) So, the rank of solutions by their freezing points is:
CoBr3 < K2SO4 < NH4 Cl
In an unknown liquid, the percentage composition with respect to carbon, hydrogen and iodine is 34.31%, 5.28% and 60.41% respectively.
Let the mass of liquid be 100 g thus, mass of carbon, hydrogen and oxygen will be 34.31 g, 5.28 g and 60.41 g respectively.
To calculate molecular formula of compound, convert mass into number of moles as follows:
Molar mass of carbon, hydrogen and iodine is 12 g/mol, 1 g/mol and 126.90 g/mol.
Taking the ratio:
Putting the values,
Thus, molecular formula of compound will be 
.
Answer:
0.41 moles.
Explanation:
Given that:
Mass of helium = 4.00 g
Initial Volume = 24.4 L
initial Temperature = 25.0 °C =( 25 + 273) = 298 K
initial Pressure = 1.00 atm
The volume was reduced to :
i.e
final volume of the helium - 10.4 L
Change in ΔV = 24.4 - 10.4 = 10.0 L
Temperature and pressure remains constant.
The new quantity of gas can be calculated by using the ideal gas equation.
PV = nRT
n = 
n = 
n = 0.4089 moles
n = 0.41 moles.
<h2>Answer : Option D) Heterogeneous mixture</h2><h3>Explanation : </h3>
A mixture in which particles are not evenly distributed and particles keep their unique properties are called as heterogeneous mixture.
Usually, in heterogeneous mixture the substances are not evenly distributed and they can be easily separated through any physical methods. Also the components retains their original/unique properties in the mixture. It usually contains various particles from different substances that are not uniformly distributed throughout the mixture.
