Answer:
Formula of oxide is 
Explanation:
The given compound consists of Fe and O.
So, mass of oxygen in sample = (mass of sample) - (mass of Fe in sample)
= (6.285 g ) - (4.396 g)
= 1.889 g
Molar mass of O = 16 g/mol and molar mass of Fe = 55.845 g/mol
So, ratio of number of moles of Fe and O (Fe : O)
= 
= 0.0787 : 0.118
= 
= 1 : 1.5
= 2 : 3
So, formula of oxide is 
P2O5 = Phosphorus pentoxide
CuO = Copper (II) oxide
NH4CI = Ammonium Chloride
Mn(OH)2 = Pyrochroite
H2O2 = Hydrogen peroxide
P4S9 = Tetraphosphorus nonasulfide
CIO2 = Chlorine dioxide
NaF = Sodium fluoride
FeSO3 = Iron (II) Sulfite
Fe(NO3)3 = Iron (III) Nitrate
Cr(NO2)3 = Chromium (III) Nitrite
NaHCO3 = Sodium Hydrogen Carbonate
H2PO4 = Dihydrogen Phosphate Ion
NaCN = Sodium Cyanide
IF7 = Iodine Heptafluoride
PCI3 = Phosphorus Trichloride
Answer:

Explanation:
Hello!
In this case, since the undergoing chemical reaction is:

We first need to identify the limiting reactant given the masses of nitrogen and hydrogen:

It means that only 0.647 moles of ammonia are yielded, so the resulting enthalpy change is:

Best regards!