Why are strong forces able to hold atomic nuclei together? a. strong forces increase the mass of neutrons. b. strong forces act only between protons at long distances. c. strong forces overcome electrostatic repulsion among protons. d. strong forces act at short distances between electrons and protons.

answer is: c. the experiment shows that the red substance experienced a chemical change.

this is chemical change (chemical reaction), because two new substances are formed (metalig liquid and gas), the atoms are rearranged and the reaction is followed by an energy change.

this is example of chemical decomposition.

chemical decomposition (analysis) is the separation of a single chemical compound into its two or more elemental parts or to simpler compounds.  

chemical decomposition is opposite of chemical synthesis.

idk i’m struggling too