How many atoms are there in 42 grams of NH3?

We know that we have 1 Atom of N and 3 Atoms of H to get 4 total atoms of NH3

Atoms = 4 Atoms * 1.488 x10^24

=5.951 x10^24 atoms of NH3

I hope this helped :)

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.