Question

Water acts as Bronsted acid as well as a Bronsted base. Give one example each to illustrate this statement.

Answer 1

Molecules or ions that can behave both as Bronsted Acid and Bronsted Base are called amphiprotic substances. With $HCl$, water acts as a base in accepting a proton from the acid.
$HCl+H_{2}O\to H_3{O}^{+}+{Cl}^{-}$
Acid Base
Water is all acid while donating a proton to ammonia
$N{H}_3+H_{2}O\to N{H}_4^{+}+O{H}^{-}$
Base Acid