1. Calculate the RFM of Fe(NO3)2

The Relative Formula Mass of Fe(NO₃)₂ is 179.8524 grams

Explanation:

The Relative Formula Mass is the mass of one mole of a compound expressed in grams, obtained by adding together the Relative Atomic Masses, RAM, of the elements which makes the compound

The Relative Formula Mass of a compound is the same as its Relative Molecular Mass

The relative formula mass of Fe(NO₃)₂ is given as follows;

The relative atomic mass of Fe = 55.845 amu

The relative atomic mass of nitrogen, N = 14.0067 amu

The relative atomic mass of oxygen, O = 15.999 amu

Therefore, we have;

The formula mass of Fe(NO₃)₂ = (55.845 + 2×(14.0067 + 3×15.999)) amu = 179.8524 amu

The Relative Formula Mass of Fe(NO₃)₂ = 179.8524 grams.

i think it's c. if you look search electronic symbol on google and then click on wiki it shows you a

the formula mass of a molecule or a compound is the sum of the atomic weights of the atoms in its empirical formula

(that's what i know about formula mass)