What is the oxidation number for CO2

You encounter a solution that is acidic and you decide to test it by adding a small amount of a strong acid. the ph lowers slightly but is approximately unchanged, and still remains acidic. what can you say about the solution? a. it is a buffer solution. b. it is not a buffer solution it is a strong acid solution. d. the solution has been neutralized. e. the solution has excess acid present

Which element would mostly likely have an electron affinity measuring closest to zero

An atom of which element reacts with an atom of hydrogen to form a bond with the greatest degree of polarity ?