Question

iron and sulfur mix and turn to a black and yellow mixture is _
chemical change
physical change

Explanation:

In a physical change, the substances retain their chemical identities. When iron and sulfur are simply mixed, no new chemical compound is formed, just a mixture of the two substances' particles. In a chemical change, new substances with different chemical properties are formed. Since here iron and sulfur are just mixed without a chemical reaction to form a new compound, it's a physical change.

Answer:

physical change