Out of the options, the best indicator is a color change since it is the only one that can't really be blamed on a physical change. you will eventually notice that during qualitative labs and some quantitative labs, usually the thing that you are looking for is either color change or the production of a precipitate to indicate the presence of a chemical reaction
A chemical change occurs when a new substance is formed or the original substance changes its identity and composition due to a chemical reaction. This is the opposite of a physical change that modifies only physical properties such as state or shape. Moreover, a chemical reaction can be identified because if often leads to a change in color, odor, the formation of bubbles or temperature change. This implies the only one that suggests a chemical change is a change of color because this occurs if the composition of a substance or substances change.
This is a chemical change because it has been lit on fire. When it is lit on fire, the fire has been made, heat has been made, and gasses produced from the fire have also been made. Because this introduces new matter to the pictures, it is a chemical reaction.
