Changes in color occurred. A new substance was formed. A physical change in the iron occurred. The original substances were present after.
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: A student performs an experiment and the results are shown below: Before- Iron filings are brown, small, and magnetic: Copper sulfate crystals are blue, brittle, and not magnetic. After- The copper formed was reddish, solid, and not magnetic: Iron sulfide solution was colorless and not magnetic. Which statement supports that a chemical reaction took place?
Possibilities:
- Changes in color occurred.
- A new substance was formed.
- A physical change in the iron occurred.
- The original substances were present after.

A new substance was formed.