Elements which appear in the same column have similar properties (periodicity). For example, all of the elements in group XVII (17), the Halogens, all react in a similar fashion; they all like to attract one additional electron and form a -1 anion.
In a chemical equation, the symbol that means “dissolved in water” is (aq).
Explanation:
CO2 is called as gas because it exist in single thermodynamics state i.e CO exist in gases state only at room temperature.
