Question

why are some of the circles marked with an \x\ for the experiment? the x tells us those containers will have a change in temperature. the x tells us to look closely for a reaction in those containers. the x tells us the reagents will always look different when combined with themselves. the x represents combining two portions of the same chemical. there would never be a change.

Explanation:

In a chemical experiment, marking circles with "X" usually indicates areas where reactions are expected or should be closely observed. There is no indication that the "X" is related to temperature change, self - combination of reagents with no change, or that reagents always look different when combined with themselves.

Answer:

The X tells us to look closely for a reaction in those containers.