Proton and neutron because e does not matter much
and the mass of atom as you already know is consist of p and n
There are many examples of chemical equilibrium all around you. One example is a bottle of fizzy cooldrink. In the bottle there is carbon dioxide (CO2) dissolved in the liquid. There is also CO2 gas in the space between the liquid and the cap
Magnesium oxide can be very bad for your health, and when we did an experiment with it in class it was white because it was so hot. It is very flammable.
I’d say A. They are theoretical in the fact that they have not been observed directly, but have been confirmed to exist through experimentation.
