Iron and sulfur react to yield iron sulfide. balance this reaction. (s) + (s) → (s)

The balanced equation  of reaction  between iron and sulfur to yield  sulfide is as below

8 Fe(s) + S8(s)→ 8 FeS (s)

 Explanation

 According  to the  law of mass  conservation , the  number   of  atoms  in the  reactant side  must be equal  to  number  of atoms in  product  side

.

By  putting   coefficient  8 in front  of Fe   and in front  of FeS ,  it   balance the reaction  of synthesis of FeS   since it make sure the number  of  atoms  are equal in both side.

for example   there are 8 atoms  of Fe in reactant  side and  8 atoms of Fe in the product side.

b is the correct

the answer is option a.