Chapter 22, Problem 5STP

To determine

To Choose: The correct option.

Explanation of Solution

Introduction:

Hydrogen ions react with molecules of water so as to produce hydronium ions.

  ${\text{H}}_3{\text{O}}^{+}$ is the chemical formula of a hydronium ion.

Of the given options, option A represents the chemical formula of a hydronium ion.

The rest are chemical formula of carboxylic acid (B. $-\text{COOH}$ ), hydroxide ion (C. ${\text{OH}}^{-}$ ) and a water molecule (D. ${\text{H}}_2\text{O}$ ).

Conclusion:

Hence,Option A. ${\text{H}}_3{\text{O}}^{+}$ is the chemical formula of a hydronium ion.