Explanation:
The given data is as follows.
Boiling point of water (
= (100 + 273) K = 323 K,
Boiling point of solution (
= (101.24 + 273) K = 374.24 K
Hence, change in temperature will be calculated as follows.

= 374.24 K - 323 K
= 1.24 K
As molality is defined as the moles of solute present in kg of solvent.
Molality = 
Let molar mass of the solute is x grams.
Therefore, Molality = 
m =
= 
As, 

x = 
= 1321.29 g
This means that the molar mass of the given compound is 1321.29 g.
It is given that molecular formula is
.
As, its empirical formula is
and mass is 30 g/mol. Hence, calculate the value of n as follows.
n = 
= 
= 44 mol
Thus, we can conclude that the formula of given material is
.
This may help you
Use an arbitrary mass, 100 g is an easy number to work with.
60% of 100 g is 60 g, there are two A's. Each A is 30 g
40 g is B, and there is only one, so B is 40 g.
<span>A<span>B2</span></span>, would have a mass of 30 g + 2*40 g = 110 g
The new percent by mass composition of A is: <span><span><span>30g</span><span>110g</span></span>∗100%=27.3%</span>
The new percent by mass composition of B is: <span><span><span><span>80g</span><span>110g</span></span>∗100%=72.7%</span></span>
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