Iron and sulfur react to yield iron sulfide. balance this reaction.

(s) + (s) → (s)

Explanation:

The unbalanced reaction of the reaction of Iron and sulfur is shown below as:-

On the left hand side,  

There is 1 iron atom and 8 sulfur atoms.

On the right hand side,  

There is 1 iron atom and 1 sulfur atom.

Thus,  

Right side, must be multiplied by 8 to balance the sulfur and,

Left side, is multiplied by 8 so to balance the whole reaction.

Thus, the balanced reaction is:-