They all just formed on top of each other like sedimentary rocks
Answer:
168°C is the melting point of your impure sample.
Explanation:
Melting point of pure camphor= T =179°C
Melting point of sample =
= ?
Depression in freezing point = 
Depression in freezing point is also given by formula:

= The freezing point depression constant
m = molality of the sample = 0.275 mol/kg
i = van't Hoff factor
We have:
= 40°C kg/mol
i = 1 ( non electrolyte)




168°C is the melting point of your impure sample.
Answer:
They aren't listed as a whole number, because an atom's mass is not always a whole number. The mass differs between types of atoms as well.
Answer:
The minimum concentration of Cl⁻ that produces precipitation is 12.6M
Explanation:
The Ksp of PbCl₂ is expressed as:
PbCl₂(s) → Pb²⁺(aq) + 2Cl⁻(aq)
The Ksp is:
Ksp = 1.6 = [Pb²⁺] [Cl⁻]²
When Ksp = [Pb²⁺] [Cl⁻]² the solution begind precipiration.
A 0.010M Pb(NO₃)₂ is 0.010M Pb²⁺, thus:
1.6 = [0.010M] [Cl⁻]²
160 = [Cl⁻]²
12.6M = [Cl⁻]
<h3>The minimum concentration of Cl⁻ that produces precipitation is 12.6M</h3>