Question

For a neutral solution which of the following statement(s) is/are correct ?

• A. The molar concentration of $H_3{O}^{+}={10}^{-7}$ at $298K$..
• B. The molar concentration of $O{H}^{-}={10}^{-7}$ at $298K$..
• C. Both $H_3{O}^{+}$ and $O{H}^{-}$ ions are not present.
• D. Both $H_3{O}^{+}$ and $O{H}^{-}$ ions are present in small but equal concentration.

Answer 1

Answer: (A), (B), (D)

Both $H_3{O}^{+}$ and $O{H}^{-}$ ions are present in small but equal concentration.

In a neutral medium , $\left[H^{+}\right]=\left[O{H}^{-}\right]=1\times {10}^{-7}mol{L}^{-1}$ at $298K$.
In water medium actually $H^{+}$ combines with $H_{2}O$ and exists as $H_3{O}^{+}$.
Hence both $H_3{O}^{+}$ and $O{H}^{-}$ are present in equal amount but as in 1 liter of solution only $1\times {10}^{-7}mol$ of $H_3{O}^{+}$ and $O{H}^{-}$are present, so their amount is very small.
Therefore option (d) is only correct and others are incorrect.