Option C: the electrons are embedded in a positive sphere.
As we know that was a wrong model and nowadays the electrons are considered to be around the nucleus, in regions called orbitals.
Weathering breaks down rock and other material
Answer : The question is to write the elements alphabetically and seperating them with commas.
So in this case for your question of Fireworks , K

,
The answer will be
K, N, O.
You have to just differentiate the elements and write them according to the alphabetical order.
All organic compounds have at least 1 carbon and 2 hydrogen atoms.