How can you use the periodic table to find the number of protons in one atom of an element? a: the number of protons is the same as the atomic number of the element. b: the number of protons is the same as the atomic weight of the element. c: the number of protons can be found by subtracting the number of electrons from the number of neutrons. d: the number of protons cannot be determined from the information of the periodic table.

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