I believe the correct answer is B
Density is proportional to molar mass, assuming pressure and
temperature remain constant. Therefore, since CO has a molar mass of 28
and CO2 has a molar mass of 44:
The relative density of CO vs air is 28/29 = 0.9655.
The relative density of CO2 vs air is 44/29 = 1.517.
Have a different number of protons
(A.) Nickel and oxygen reacting chemically could create a compound. (Most likely some sort of oxide)
The pure silver is only made up of one element, so it can't be a compound.
The sandwich and all it's components may contain chemical compounds, but is not a compound in itself.
While it is possible that the material the nails are made out of is a compound, we are not given this information. Simply stating that nails (no matter the size) are in a box, does not make it a compound.
Answer:
Electrons on atoms have different amounts of energy proportional to the distance of their orbital from the nucleus. So in the flame, electrons get excited and pushed to higher energy levels by the heat energy. When they fall back down, they give off photons of light of different colors, based upon how far they fall.