Question

Which of the underlined substance is acting as a base?

Answer 1

Is it not `C`, `"bicarbonate ion...?"`

Explanation:

A base is a proton acceptor; an acid is a proton donor.

For `A`, sulfuric acid DONATES A PROTON.

For `B`, hydrogen cyanide acid DONATES A PROTON.

For `D`, chloroacetic acid DONATES A PROTON.

But for `C.` bicarbonate ion ACCEPTS a proton...to carbonic acid which dissociates to carbon dioxide and water...

`HNO_2(aq) + HCO_3^(-) rarr H_2CO_3(aq) + NO_2^-`

Another way we could represent carbonic acid is as...`H_2O*CO_2-=H_2CO_3`...i.e. water soluble carbon dioxide...