Bicarbonate ion is an example of a
a. an acid
b. a base
c. an acidic salt
d. a basic salt
e. an amphoteric substance

It is both. We normally think of it as a base because it raises the pH of water by accepting a proton,

HCO3- + H2O <> H2CO3 + OH-

but if you add bicarbonate to a strongly basic solution, it actually lowers the pH by donating a proton.

HCO3- + OH- <> CO3(2-) + H2O. That's why it is an amphoteric substance

16- counting by fours

C. chemical changeshope i : )