An atom of element a has 47 protons. what would the element's atomic number be?

Any atom that contains exactly 47 protons in its nucleus is an atom of silver. The number of protons in atom of silver is therefore 47. Example 3 - Numbers of Protons in Neon: The element Neon (Symbol Ne) has the Atomic Number of 10.

answer: c.

explanation:

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.