The fourth one is correct yw
Because the sulfur ion has a negative two charge, the formula would be Fe2S3
Answer: The molecular formula will be 
Explanation:
Molecular formula is the chemical formula which depicts the actual number of atoms of each element present in the compound.
Empirical formula is the simplest chemical formula which depicts the whole number of atoms of each element present in the compound.
To calculate the molecular formula, we need to find the valency which is multiplied by each element to get the molecular formula.
The equation used to calculate the valency is:

empirical mass of 
Molecular mass= 214 g/mol

Thus molecular formula will be 
I think answer should be a. Please give me brainlest let me know if it’s correct have a great night
The answer is 77kg I hope this helped good luck!