Answer:
Molar mass of unknown solute is 679 g/mol
Explanation:
Let us assume that the solute is a non-electrolyte.
For a solution with non-electrolyte solute remains dissolved in it -
Depression in freezing point of solution, 
where, m is molality of solute in solution and
is cryogenoscopic constant of solvent.
Here 
If molar mass of unknown solute is M g/mol then-

So, 
so, M = 679 g/mol
The answer is 236.5 J/K
According to Δ G formula:
ΔG = ΔH - TΔS
when ΔG is the change in free energy (KJ)
and ΔH is the change in enthalpy (KJ)= ΔHvap * moles
= 71.8 KJ/mol * 1.11 mol
= 79.7 KJ
and T is the absolute temperature (K)= 64 °C + 273°C = 337 K
Δ S is the change in entropy KJ/K
by substitution:
when at equilibrium ΔG = 0
∴ΔS = ΔH / T
=79.7 KJ/ 337 K
= 0.2365 KJ/K
= 236.5 J/K
The correct answer to this question is that the length of 14 is it’s half Which would be 7
Answer : The final equilibrium temperature of the water and iron is, 537.12 K
Explanation :
In this problem we assumed that heat given by the hot body is equal to the heat taken by the cold body.


where,
= specific heat of iron = 560 J/(kg.K)
= specific heat of water = 4186 J/(kg.K)
= mass of iron = 825 g
= mass of water = 40 g
= final temperature of water and iron = ?
= initial temperature of iron = 
= initial temperature of water = 
Now put all the given values in the above formula, we get:


Therefore, the final equilibrium temperature of the water and iron is, 537.12 K