Which of the following has a standard enthalpy of formation value of zero at 25 degrees C and 1.0 atm

Question

A. Fe(s)
B. Fe2O3(s)
C. FeSO4(s)
D. FeSO4(aq)
E. FeS3(s)

and what is enthalpy or how do you find it

Answer 1

All elements have a delta H_f of zero at 1.0 atm and 25^{o C.}

Answer 2

So I need to find the Hf of each of those equations

Answer 3

Absolutely not.
All ELEMENTS have a standard heat of formation of zero at 1.0 atom and 25 degrees C. Which of the 5 answers listed is an ELEMENT (the other four are, of course, compounds).

Answer 4

Fe(s) is an element right

Answer 5

yes.

Answer 6

Fe, all other answers are compounds so they can not have an enthalpy of 0 at 25 C.