Answer:
17,932.69 g/mol is the molecular weight of the substance.
Explanation:
Using Beer-Lambert's law :
Formula used :
where,
A = absorbance of solution = 1.04
c = concentration of solution =?
l = length of the cell = 1 cm
= molar absorptivity of this solution = 18,650 
Now put all the given values in the above formula, we get the molar absorptivity of this solution.
c = 

V = Volume of the solution in L
Molecular weight of the substance = x
V = 100 mL = 0.1 L
Mass of the substance = 100 mg = 0.1 g

x = 17,932.69 g/mol
17,932.69 g/mol is the molecular weight of the substance.
Gosh, I love chem!
[H2O]/t should be 0.085M/s
this is because of the coefficients in front of H2S and H2O being the same.
the significance of this answer is that the H2S disappears at the same rate H2O appears.