Atomic weights are weighted averages calculated by multiplying the relative abundance of each isotope by its atomic mass and then summing up all the products.
L'air n'est pas un mélange gazeux, donc la réponse serait le verre
Balanced chemical reaction: 2KClO₃ → 2KCl + 3O₂.
Potassium is metal from first group of Periodic table of elements, it has always oxidation number in compound +1.
Chlorine in the reactant state has oxidation number +5 (+1 + x + 3 · (-2) = 0) and it is reduced to -1 (+1 + x = 0) in the product state.
Oxygen in the reactant state has oxidation number -2 (+1 + 5 + 3 · x = 0) and it is oxidized to 0 (in molecule of oxygen) in the product state.
El Niño = the boy, La Niña = the girl. You can tell from the ending and the first word.
