Question

Complete the following reaction:
$H_{2}O\left(l\right)+$$\rightleftharpoons H_3{O}^{+}+$

• A. $H_{2}O$(l)
• B. $O{H}^{-}$(aq)
• C. $O_2$(g)
• D. $H_2$(g)

Answer 1

Answer: (A), (B)

The correct options are
A $H_{2}O$(l)
B $O{H}^{-}$(aq)

This reaction is known as autoprotolysis or self ionisation of water. It occurs due to the amphoteric nature of water.
Water acts as an acid by donating $H^{+}$ ion and forms hydroxyl ion, $O{H}^{-}$. Simultaneously, it acts a base by accepting $H^{+}$ ion to form hydronium ion, $H_3{O}^{+}$.
$H_{2}O\left(l\right)+H_{2}O\left(l\right)\rightleftharpoons H_3{O}^{+}\left(aq\right)+O{H}^{-}\left(aq\right)$